HomeMy WebLinkAboutSWP272704(1) ' GEOTECHNICAL ENGINEERING STUDY
SW 23RD STREET DRAINAGE CHANNEL DEEPENING
RENTON,WASHINGTON
' HWA Project No. 8919-200
' October 5, 1998
Prepared for:
' R. W. BECK
t
HWAGEOSCIENCES INC.
U►R",
HWAGEOSCIENCES INC.
19730-64TH AVE. W., SUITE 200
LYNNWOOD, WA 98036-5957
October 5, 1998 TEL. 425-774-0106
FAX.425-774-2714
HWA Project No. 8919-200 E-MAIL hwa@hongwestwest.com
R.W. Beck
' 1001 Fourth Avenue, Suite 2500
Seattle, Washington 98154
' Attention: Mr. Michael Giseburt, P.E.
' Subject: GEOTECHNICAL ENGINEERING STUDY
SW 23'd Street Drainage Channel Deepening
Renton,Washington
1 Dear Mike:
' Pursuant with your request, HWA GeoSciences Inc. (formerly Hong West & Associates
and Hong Consulting Engineers) performed a geotechnical engineering study for the
proposed SW 23id Street Drainage Channel Deepening project in Renton, Washington.
The results of our study are presented in the accompanying report.
Previously, we prepared a geotechnical report titled Geotechnical Soil Investigation,
' Panther Creek, SR 167—P-9 Channel Project, dated June 2, 1989. The original report
contained results of subsurface explorations along the project alignment and geotechnical
recommendations for a water level control structure, a culvert beneath SR 167, highway
embankment protection measures, and channel considerations for the P-9 channel. The
following report includes results of additional subsurface explorations along the P-9
channel and geotechnical recommendations which specifically address the P-9 channel,
including channel side slopes, erosion, dewatering, and construction considerations.
1 We appreciate the opportunity to provide geotechnical services on this project. Should
you have any questions or comments, or if we may be of further service, please call.
' Sincerely,
HWA GEOSCIENCES INC.
David L. Sowers, P.E. Sa H. Hong, P.E.
' Geotechnical Engineer Principal Geotechnical Engineer
GEOLOGY
GEOENVIRONMENTAL SERVICES
HYDROGEOLOGY
GEOTECHNICAL ENGINEERING
TESTING & INSPECTION
1
TABLE OF CONTENTS
' Page
1.0 INTRODUCTION................................................................................................ 1
' 1.1 GENERAL .................................................................................................. 1
1.2 PROJECT DESCRIPTION............................................................................... 1
1.3 PROJECT BACKGROUND............................................................................. 1
2.0 FIELD AND LABORATORY INVESTIGATION............................................... 2
2.1 FIELD INVESTIGATION................................................................................ 2
2.2 LABORATORY TESTING.............................................................................. 2
' 3.0 SITE CONDITIONS......................................................................................... .. 2
3.1 SURFACE CONDITIONS ................................................................. ........ .. 2
3.2 REGIONAL GEOLOGY.......................................................... ............ .. 3
3.3 SUBSURFACE CONDITIONS........................................ ..... . ............. ........ 3
3.4 GROUNDWATER CONDITIONS........................... .............. . .. . ...... ......... 4
4.0 CONCLUSIONS AND RECOMMENDATIONS...... ......... .............. ...... ......... 4
4.1 SUNDAA.RY...........I....................... ....... ......... ...... ....... ......... ...... ......... 4
4.2 CHANNEL SIDE SLOPES................ ......... ........ ............... ......... ...... ......... 5
4.2.1 Allowable a lopes nd a Sta ilizatio easur s... ......... 5
4.3 CONSTRUCTI ONSIDE TIO S.. ...... ...... ...... .................. ...... ......... 6
4.3.1 Exc vati . ...... ...... ..... .. ...... ..... ...... .................. ... ........... 6
' .3.2 at rial .... ...... ...... ..... .. ....... ... ...... ................................... 7
4.3.3 ce ter/ ou dwater Cont o ...... ................................... 7
4. I AL OUNDWA L LS WE IMPACTS..................... 8
5.0 UNC RT IE T ON 8
6.0 RE RE ICE 10
LIST OF GURES OLLOWING TEXT
Figure 1. Vicinity Map
1 Figure 2. Site and Exploration Plan
Figure 3. Generalized Subsurface Cross Section A-A'
Figure 4. Generalized Subsurface Cross Section B-B'
Appendix A: Field Exploration
' Figure A-1. Legend of Terms and Symbols Used on Exploration Logs
Figures A-2 — A-3. Logs of Borings BH-1 and BH-2
' Table of Contents Continued
Appendix B: Laboratory Investigation
' Figure B-1. Grain Size Distribution Test Results
Figure B-2. Plasticity Characteristics
' Appendix C: HCE Explorations (1989)
Logs of Hand Auger Holes HB-1 through HB-3
I
8919200.doc 11 HWA GEOSCIENCES INC.
' GEOTECHNICAL ENGINEERING STUDY
SW 23RD STREET DRAINAGE CHANNEL DEEPENING
RENTON, WASHINGTON
1.0 INTRODUCTION
' 1.1 GENERAL
This report presents the results of our geotechnical study for the proposed SW 23`d Street
Drainage Channel Deepening project in Renton, Washington. The purpose of thi dy
was to explore and evaluate the surface and subsurface conditions at the si , and prc vide
' conclusions and geotechnical recommendations for deepening the o channel alo the
south side of SW 23`d Street from Lind Avenue to East Valle ghvy
' A proposal for the performance of this study was bmitte by A to R. B ck on
June 9, 1997. Authorization to proceed with Is s pe o wo subse uen ly given
by R.W. Beck in a subconsultant agreement ted J e 18 19 . T e sco of work
' completed for the project, as c 'be herei s in general agr ent wi h th t outlined
in the subconsultant agree ent.
' 1.2 PROrstan N
' Our uncleof t e Channel pe ng pro' t is a on discussions with and
informati n pr vid d b t e C' of R t n a d Mr. ' e Giseburt of R.W. Beck.
Presently, an c pen har ne. aloi ig t e so ide of SW 23`d Street conveys surface water
from a culvert un rn th Eas Val y Highway to the east side of Lind Avenue (the
direction f fl is e t t t). The City has proposed two options for the existing
drainage channel. a first option involves deepening the channel bottom 3 to 4 feet
below the exi ' g grade. It is anticipated that lowering the bottom of the existing channel
will impro e the flow of surface water along this corridor. The second option is simply
the"do nothing" approach. In this case, channel deepening would not take place and the
channel would remain essentially untouched, with the exception of construction activities
1 and improvements at the road under-crossings in the future. The following report presents
geotechnical recommendations for the proposed channel deepening option described
above.
1 1.3 PROJECT BACKGROUND
Our firm, formerly known as Hong Consulting Engineers, Inc. (HCE), originally prepared
a geotechnical report titled Geotechnical Soil Investigation, Panther Creek, SR 167—P-9
' October 5 1998
HWA Project No. 8919-200
Channel Project, dated June 2, 1989 (Reference 1). This report summarized the results of
HCE's subsurface explorations and provided geotechnical recommendations for
improvements along Panther Creek from SR 167 to Lind Avenue. The report provided
geotechnical recommendations for the under-crossing at SR 167, a water level control
structure on the east side of SR 167, highway embankment protection measures, and a
brief discussion of geotechnical design and construction recommendations for the channel
' deepening portion of the project. The original report provided recommended allowable
side slopes and general erosion control measures for the P-9 channel.
More recently, the Washington State Department of Transportation (WSDOT) prepared a
technical memorandum regarding the SR 167 culvert under-crossing. The me n um,
dated March 4, 1997, included results of WSDOT borings and geotechni
recommendations on culvert installation.
' 2.0 FIELD AND LABORATORY INV ESTI ON
2.1 FIELD INVESTIGATION
' On June 20, 1997, an HWA g chm al en ne r o ery the d ' ' g oft o -foot
deep borings (designated -1 and B 2) a th pp xi ate cations sho n the Site
' and Exploration P Fi re 2 e b ring w r pe ed t observe th sence and
depth to dwater, an soi co diti ns on a ali ent. The borings were drilled
with a tra ;k-mounted o ile 11 ri , o d and opera a by olocene Drilling of
Pacific, Washii gt un ei subcontra to el d a ration methods are described
and summary l gs ire a ent . Ap a ix
' 2.2 LAB RA R TE T G
Soil samp es o aine at s ed intervals within the borings were placed in air-tight bags
and taken to our la ratory for further examination and testing. Select soil samples were
tested for o' re content, grain size distribution, and plasticity characteristics (Atterberg
Limits). iscussions of laboratory test methodology and test results are presented in
Appendix B.
' 3.0 SITE CONDITIONS
3.1 SURFACE CONDITIONS
The channel alignment on the south side of SW 23`d Street extends approximately 1,230
feet from East Valley Road to Lind Avenue. The alignment lies in a marshy, lowland area
' filled with brush and small trees. The slope on the northern side of the channel (south side
of the 23`d Street roadway embankment) is sloped from approximately 1'/2H:1 V to
8919200.doc 2 HWA GEOSCIENCES INC.
' 1998
October 5,
HWA Project No. 8919-200
2'/2H:1V(horizontal:vertical). Surface water in the drainage channel flows east to west.
Parcels on both sides of SW 23`d Street extending from East Valley Highway to Lind
Avenue are considered wetland areas.
' 3.2 REGIONAL GEOLOGY
Geologic information for the site was obtained from the Geologic Map of the Renton
Quadrangle, King County, Washington (Reference 4). The geologic map indicates that
the area is generally underlain by peat and recent alluvial deposits. Alluvium, or river-
deposited soils, typically consist of interbedded, discontinuous layers of sand, silt, clay,
and organic soils. Alluvium is typically unconsolidated and generally exhibits to ar
strength and high compressibility.
Local geologic and geotechnical information was also obtaine om on inal
geotechnical study completed by our firm (Reference 1) al ng the pr al ent. We
' also relied on subsurface information obtained fr explo do completed for the nearby
Olympic Pipeline Culvert Replacement (Refer nce
' 3.3 SUBSURFACE CONDIT S
Based on the resul of ou ex tion an ex 1 ati s y of ers, the site a ars
' generally u ain b 11 al an s a sil , c sten th the geologic map. Along the
SW 23`d Street alignm t, the uviu is erlam by fil s ils u ed to construct the
roadway. In m area at and or nic ilts w obs overlying the recent
alluvium. The sub urfa a nit cou er d i the a orations are described below in the
order of s rati rap 'c s q enc in whic a ere deposited, with the youngest units
' described rst, an are phi illy e ' don Figures 3 and 4.
• Fill: 11 m erial we served extending about 7'h feet below the ground surface.
' The fi soils ge erally consisted of medium dense, poorly graded sand with gravel and
varyin s' ontent. These fill materials were likely placed to construct the existing
access road for the Seattle Water Department. We anticipate the fill soils directly
underlie this access road, and do not anticipate these fill materials will be encountered
in the bottom of the new channel.
' • Peat/Organic Silt: In explorations performed by our firm (Reference 1), peat and
organic silt were observed at the ground surface to depths of 9 feet. The thickness of
' these soft organic soils was less below SW 23`d Street (approximately 3 feet thick)
most likely because these soils were partially overexcavated when fill was placed and
the roadway constructed.
8919200.doc 3 HWA GEOSCIENCES INC.
' October 5 1998
' HWA Project No. 8919-200
• Recent Alluvium: Alluvial soils were encountered directly beneath the fill in borings
' BH-1 and BH-2. In our earlier explorations (Reference 1), alluvium was observed
underlying the peat and organic silts. Alluvium observed in the explorations generally
consisted of interbedded, very loose to loose, sand and silty sand, to soft silt with
' varying amounts of sand. The alluvium extended to the full depth in each exploration.
' 3.4 GROUNDWATER CONDITIONS
Groundwater was observed in the borings BH-1 and BH-2 at depths of approximately 5
' feet below the existing ground surface (approximately Elevation 11 feet using NGVD 29).
Groundwater was observed in the our hand borings at depths of I to 2 feet belo
ground surface (approximately Elevation 11 to 12 feet). Surface water w so observed
' in the channel at the time of our site visit.
In addition to our explorations, the NRCS (National Reso rces Con 1 n Service) has
' installed monitoring well near each end of the pro' t alig en . he NRC m 'tored
groundwater levels for a 9-month period be en 1 97 an 19 8 onito ng ell
readings indicate an average groundwater ele ation f bet een Elev tion 8 and 0 feet
' (NGVD 29), depending on t eason; ghe t ter evel eadi were o ery d in the
fall and winter months, to est readings in th s er o ths. Standing water ii the
' adjacent et an s w m nit ed nd r cod d b theNR S. The identified
surface w r in ditch a Lin en w ch lcally a ged from Elevation 7 to 8 feet;
peak level wer bse a in ove er 1 7 at Elevati n 9 f t. Surface water in ditches
' along Eas Va ley 'gh ha simila le is r r un th highest groundwater levels
observed n th fall
1 Based on he ov av it le data, 't ears that groundwater levels change in response
to rainfall nd i of ea .
' .0 CONCLUSIONS AND RECOMMENDATIONS
4.1 SUMMARY
We understand the SW 23" channel deepening project will extend the bottom of the
' channel approximately 3 to 4 feet below the existing grade, as shown on Figure 4. The
stability of the channel side slopes will depend on the steepness of the cut. We anticipate
slopes at angles of 2'/zH:IV or flatter are relatively stable and bank stabilization measures
' will include only revegetating. Excavations cut to 2H:1 V will be moderately stable and
should be further stabilized using rock blankets that cover the slopes. Slopes excavated to
1'/2H:1 V are marginally stable. At this angle, we recommend over-building the slopes
' using compacted fills and then cutting the slope/embankment back to 1'/2H:1 V.
8919200.doc 4 HWA GEOSCIENCES INC.
October 5, 1998
HWA Project No. 8919-200
The level of erosion control measures that are implemented will depend on the proposed
angle of the slope. Erosion control measures are important to the serviceability of the
channel, as erosion can begin to undermine the banks and impact their overall stability.
Sloughing soils can also begin to fill the channel and affect the drainage performance of
' the channel. Several bank stabilization measures are provided in the following report.
' Dewatering measures will be required during channel deepening if a steeper angle than
2'/2H:l V is excavated or if construction occurs during wet seasons of the year. We
anticipate surface water can be controlled using either low earthen berms/ditches, sumps,
' pumps, or a combination of the above. Based on the proposed elevations of the channel
we do not anticipate well points or wells will be necessary to dewater. Howev , e level
of dewatering that will be required for the project will depend on the tim year,
methods of construction, groundwater level at time of constructio the soil
conditions encountered.
' The following report sections provide recomme ons f all able side ope ,
construction considerations, bank stabilizatio and a osion con , 1 pacts o adjacent
' utilities, general earthwork, dewat ' , and i pacts n re 'onal su ce wa era d
groundwater levels.
' 4.2 CHANNE E O ES
4.2.1 All wab ide I es and nk abilization faoes
' The existi g slope pe n t ort de o h ch el i nerally sloped between 1'hH:1 V
and 2'/ZH: V. Sta ility these s pes 1 e ndent on several factors including slope
' soils, their rela ive en ty gro nd at vel, and vegetation. The long-term
performance o t ch nnLlsid slopes will also be dependent on the volume and velocity
of surface at r flo 'ng tugh this drainage swale. Based on our subsurface
' exploratio s and lysis, the existing slopes are relatively stable under static loading
condition4,.-
We recommend new slopes be laid back at angles of 2'/2H:1 V or flatter if possible. While
steeper slopes can be used, the most stable slopes and those requiring the least amount of
' bank stabilization measures, are those that are the flattest. The following section presents
three options for slope angle, and within each of the options are relevant bank stabilization
measures and construction methods which should be considered.
• 2V2H:1V to 3H:1V slope, These slope angles will provide the most stable
condition with minimal bank stabilization and maintenance measures. These angles
' will also be the least costly of the slope angles proposed herein because of reduced
dewatering and slope construction costs. We understand that there is sufficient
8919200.doc 5 HWA GEOSCIENCES INC.
' October 5 1998
' HWA Project No. 8919-200
space south of the channel to accommodate this range of slope angles. Slopes at
these angles may be excavated and prepared in partially or fully submerged
conditions. Measures to control erosion can simply include using vegetation/jut-net
matting to protect the slope. Establishment of vegetation will be relatively simple
and will occur quickly.
' . 2H:1V slope, At this slope angle, the soils observed in our explorations are less
stable than the 2'/2H:1 V slope, particularly when submerged, and are moderately
susceptible to the effects of channel erosion, particularly during storm events.
Vegetation alone will be sufficient to protect and maintain stable slope conditions
above the water level in the channel. However, below the water table we
recommend placing 8 inches of 4-inch minus rock fill (either roun or angul
' faces) on the slope. Rock fill should also extend up the slo roximate ee
feet above the average water level in the channel to a unt fo o free oard
effect. Placement of a rock fill on the face will miti ate ero ' prob ms and will
help maintain the overall stability of the
' 1Y2H:1V or steeper slope, this inc nation the slopes will a mar inal y stable,
even with implement of ba sta liz ion ea res particu rly hen
excavations extend elow t e w er t le 1 ca atio s will have be
' perform n mp tel dry co itio s. co t ct sl pes at thes ngles, we
recJe
ove ex ava a p rtio of a exist n em ankment and subgrade to
theepth n replacin it wi well c mpa t d ; fill materials include
' gra itn r rus roc P ace ent e s and compaction are described
in .2. F llo n con cti n the surface of the slopes should be
covered4-i c mins gala and vegetated with deep-rooting plants.
We nd g inst his pe angle unless there is limited right-of-way or other
ext cir um t s. This option is the most expensive to construct and
mai slope options presented herein.
All slopes ent of the slope angle should be revegetated following excavating.
Other bank stabilization options include using fascines (bundles of long, live cuttings laced
together and secured to the bank) or cribwalls (Reference 4).
' 4.3 CONSTRUCTION CONSIDERATIONS
' 4.3.1 Excavations
We anticipate excavations for the channel can be accomplished with conventional
earthwork equipment such as backhoes and trackhoes. Excavation of the channel must be
' performed in a manner which will not impact existing utilities or roadways. We
recommend steel sheeting be placed over the SW 23`d Street roadway to distribute heavy
' 8919200.doc 6 HWA GEOSCIENCES INC.
October 5 1998
' HWA Project No. 8919-200
equipment loads that would otherwise apply too heavy of a point load directly over the
' utilities and potentially cause damage to them.
' 4.3.2 Materials
Constructing slopes at 1'/2H:1 V will require an imported fill material. We recommend
using materials meeting the specification for Crushed Surfacing Based Course or Gravel
' Borrow, as described in Sections 9-03.9(3) and 9-03.14(1), respectively, of the 1998
WSDOT Standard Specifications for Road, Bridge, and Municipal Construction
(Reference 6). Fill should be placed and compacted in loose horizontal lifts. Fill
placement should extend beyond the design slope limits, essentially over-buildin slope
to 2H:1 V or flatter. Once the fill has been placed, the bank can be cut bac the d sign
' slope angle, i.e. 1'hH:IV, and the face further compacted with the r tory plate.
Based on our explorations, the native soils contain a high rcentage s an have a
moisture content over optimum (ideal moisture c tent to achi maximu de sity
during re-compaction). For these reasons, w reco en aga nst -using ati a soil for
slope embankments or other structural uses. ative oils ay a us d as fil in r on-
settlement sensitive and non- ctura areas
4.3.3 ;ter
fac r/ ou dw ter o ro
Surface and gro nd wat ou be xpected du cha el deepening at all times
' of the ye n ted i ection 3. he 1 west ace and groundwater level
readings N iere takc n in hc drie umm r on s. ecommend channel deepening be
performe in t e s mm r o t at roun ate and surface water are at their lowest levels
of the year an so hat a pag int o xcavations will have less impact on
constructi n.
' The type f and a unt of dewatering required during construction will depend on several
factors, i lulu ' the relative depth to groundwater, the proposed slope angle, the
conditions encountered and the depth of the channel. As described above, slope angles of
2'/ZH:1 V can probably be performed in submerged conditions. The 1'/2H:1 V slopes,
conversely, require nearly dry conditions to construct and should include measures to
' dewater or re-route surface water around excavations. Re-routing of surface water
around sections of the channel area should be confined to small areas if possible.
Based on excavations performed during construction of the nearby Olympic Pipeline
Culvert Replacement project (HWA, 1998), groundwater seepage during the drier summer
months is anticipated to be controllable with sumps and pumps where excavations extend
' only several feet below the average groundwater level. However, wells will likely be
required when excavations extended 4 feet or more below the natural groundwater table.
' 8919200.doc 7 HWA GEOSCIENCES INC.
' October 5, 1998
' HWA Project No. 8919-200
Temporarily lowering the groundwater table during excavating several feet below the
' bottom of the nearby utilities is not expected to cause settlement. Longer-term or
permanent lowering of the groundwater table is expected to be very minimal, will probably
not extend below the base of the existing utilities, and should not create settlement
' problems for the existing facilities.
The effectiveness of this dewatering plan would depend on the amount of groundwater
' encountered in the excavation. Where large volumes of water are encountered during
excavating, e.g. wet weather construction, or for dewatering larger areas, well points
t should be considered. Well points should be spaced to provide controllable dewatering
and excavating without impacting nearby utilities. Prior to constructiot
o c r
should determine an appropriate dewatering scheme and submit a dewaplan to the
' project engineer for review.
' 4.4 REGIONAL GROUNDWATER LEVELS AND WETL IMPA
Placement of a channel liner material has been rese ted a an pt' to ma tai 'ng
and/or improving surface water flows along t e SW 3`d S reet alig ent. In our opinion,
' soils at the base of the existin anne botto a d at the I ropos annel Ott m are
low permeability soils and vary only sli htly n c sist ncy at t ese two dep hs. Based on
' the anticipated c ions we o t e pec a a el 'ne pla ed on the si opes and
bottom of channel it be g ' ca tly va geou ei her o the flow of surface
water thr ugh the area r reventin surfa a water perc 1 tion In addition, siltation of
' the channel boo will o cur over ti e a d e rn t cannel bottom to near its
original c ndit on llo i g c ructi n.
' Based on he IS epo epa red y Beck(Reference 5), impacts to the wetland
appear to be al. Ou an lysis of subsurface conditions supports a similar conclusion.
' 5.0 UNCERTAINTIES AND LIMITATIONS
We have I repared this report for use by the City of Renton and R. W. Beck in design of a
tportion of this project. This report should be provided in its entirety to prospective
contractors for bidding or estimating purposes; however, the conclusions and
' interpretations presented should not be construed as a warranty of the subsurface
conditions. Experience has shown that subsurface soil and groundwater conditions can
vary significantly over small distances. Inconsistent conditions can occur between
explorations and may not be detected by a geotechnical study. If, during future site
operations, subsurface conditions are encountered which vary appreciably from those
described herein, HWA should be notified for review of the recommendations of this
' report, and revision of such if necessary.
' 8919200.doc 8 HWA GEOSCIENCES INC.
1
October 5, 1998
' HWA Project No. 8919-200
We recommend that HWA be retained to review the plans and specifications and to
' monitor the geotechnical aspects of construction, in particular construction dewatering, if
necessary, and excavating.
' This firm does not practice or consult in the field of safety engineering. We do not direct
the contractor's operations, and we cannot be responsible for the safety of personnel other
' than our own on the site; the safety of others is the responsibility of the contractor. The
contractor should notify the owner if he considers any of the recommended actions
presented herein unsafe.
O.O
We appreciate this opportunity to be of service.
Sincerely,
' HWA GEOSCIENCES INC.
1
David L. owers E. Sa H. Hong, P.E.
Geotec ngineer Principal Geotechnical Engineer
' 8919200.doc 9 HWA GEOSCIENCES INC.
' October 5 1998
' HWA Project No. 8919-200
' 6.0 REFERENCES
1. Hong Consulting Engineers, Inc., 1989, Geotechnical Soil Investigation, Panther
Creek, SR 167—P-9 Channel Project, Renton, Washington, consultant report
' prepared for R. W. Beck, dated June 2, 1989.
2. HWA GeoSciences, 1998, Olympic Pipeline Culvert Replacement, SW 23'd Street and
Lind Avenue, Renton, Washington, consultant report prepared for R. W. Beck, dated
May 11, 1998.
3. Johnson, A.W. and J.M. Stypula, editors, 1993, Guidelines for Bank StabilizRffol
Projects in the Riverine Environments of King County, King County partmen of
' Public Works, Surface Water Management Division, Seattle, gton.
4. Mullineaux, D.R., 1965, Geologic Map of the Renton uadran n Co nty,
' Washington, U. S. Geological Survey.
5. R.W. Beck,Plan And Environmental Im act St eme t, Yolume , Dra t, cc nsultant
' report prepared for the C' Re on, d to De emb r 199
6. Washington S e De art f T ans ort ti n/ eiican ublic WorkWsociation,
1998, lard S ci scat n for oa , B ' e, d I 11uniipal Construction.
' 8919200.doc 10 HWA GEOSCIENCES INC.
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' NOT TO SCALE
SW 23RD STREET DRAINAGE VICINITY MAP
CHANNEL DEEPENING
H GE0SCEN jW RENTON, WASHINGTON
' PROJECT NO.:S91 9-ZOO FIGURE: 1
D: JOBS 8919—TOO 8919OOO1.DWG
I
n I
Li
1 �
HB-2
' EXISTING DITCH B'
I
I
1
' LEGEND
0' 50' 100' 200'
- BH-1 BORING DESIGNATION AND
APPROXIMATE LOCATION (HWA, 1997) SCALE: 1"-100'
' - HB-1 HAND AUGER BORING DESIGNATION AND
APPROXIMATE LOCATION (HCE, 1989)
' A AP SW 23RD STREET DRAINAGE SITE AND
t--# cRoss SECTIONS i CHANNEL DEEPENING EXPLORATION PLAN
' FMGEOSCIENCES INC. RENTON, WASHINGTON
REFERENCE: Base map provided by R.W. BECK. PROJECT N0.:8919-200 FIGURE: 2
D: JOBS 8919-200 89190002.DWG
A At
WEST LIND AVENUE EAST
EXISTING GROUND
' 20 SURFACE EAST VALLEY
ROAD 20
a
10 10
Uj
LLJ
Ld
� r
m =
m
Z 0 ?T - ? 0 z
' O . . . . . . _
O
a
J ? . . . . .
Ld
-10 -10
' -20 -20
HORIZONTAL SCALE: 1"=100'
' 0' 50' 100' 200'
0' 5' 10' 20'
VERTICAL SCALE: 1"=10'
NOTES
' LEGEND
1. Refer to Figure 2 for approximate cross section location.
BORING DESIGNATION
= AND APPROXIMATE LOCATION FILL: Medium dense, SAND with silt and gravel. 2. Subsurface conditions shown are based on interpolation
co
between widely spaced borings and should be considered
TOP OF EXPLORATION approximate.
29 BLOW COUNT FROM ' - ORGANIC SILT 3. Elevations using NGVD 29 datum.
STANDARD PENETRATION TEST PEAT/
(Blows/Foot)
_ WATER LEVEL OBSERVED
' DURING INVESTIGATION RECENT ALLUVIUM (SILT): Very soft to soft SILT with
some sand. SW 23RD STREET DRAINAGE GENERALIZED SUBSURFACE
BOTTOM OF EXPLORATION CHANNEL DEEPENING CROSS SECTION A—A�
'
RECENT ALLUVIUM (SAND): Very loose to loose, silty HmGEosaENCES INC.RENTON, WASHINGTON?— ? INFERRED GEOLOGIC CONTACT SAND to SAND.
PROJECT NO.:8919-200 FIGURE: 3
D: JOBS 8919-200 8919003.DWG
B B,
NORTH SOUTH
' UTILITIES SW 23RD STREET
20 (TYPICAL) 20
= EXISTING CHANNEL
m N GRADE
m
' 10 v, 10
Uj
LL
Z
0 0 PROPOSED 0 0
i Q CHANNEL GRADE Q
w w
J J
W W
-10 -10
-20 -20
HORIZONTAL SCALE: 1"=100'
0' 50' 100' 200'
' 0' 5' 10' 20'
VERTICAL SCALE: 1"=10'
NOTES
i LEGEND
T 1. Refer to Figure 2 for approximate cross section location.
= m BORING DESIGNATION
AND APPROXIMATE LOCATION FILL: Medium dense, SAND with silt and gravel. 2. Subsurface conditions shown are based on interpolation
m = between widely spaced borings and should be considered
TOP OF EXPLORATION approximate.
29 BLOW COUNT FROM
STANDARD PENETRATION TEST PEAT/ORGANIC SILT 3. Elevations using NGVD 29 datum.
(Blows/Foot)
WATER LEVEL OBSERVED
DURING INVESTIGATION RECENT ALLUVIUM (SILT): Very soft to soft SILT with
some SAND. SW 23RD STREET DRAINAGE GENERALIZED SUBSURFACE
BOTTOM OF EXPLORATION CHANNEL DEEPENING CROSS SECTION B-B'
' RECENT ALLUVIUM (SAND): Very loose to loose, silty �;]�AjA �r��Z�T C INC RENTON, WASHINGTON
?— ? INFERRED GEOLOGIC CONTACT SAND to SAND. ;1r�11 G GPI J lj�l
PROJECT NO.:891 9 ZOO FIGURE: 4
D: JOBS 8919-200 8919004.DWG -
e APPENDIX A
' FIELD EXPLORATION
1
APPENDIX A
FIELD EXPLORATION
The field investigation consisted of drilling and sampling two exploratory borings to
maximum depths of approximately 24 feet. The field exploration program was completed
on June 20, 1997 under the full time observation of an HWA engineer. The borings were
located approximately in the field by taping distances from known site features and plotted
on the Site and Exploration Plan, Figure 2. A legend to the terms jb n
the exploration logs is presented on Figure A-l. Summary boring sented on
Figures A-2 and A-3.
Geotechnical drilling was performed by Holocene Drilling f Pacifito , under
subcontract to HWA. The boring was drilled wi Mobiletr - ll 'g
advancing a 4'/<-inch I.D., continuous flight h llow em a ger.
' During drilling, the HWA re ntati rec de pe ine info in soil
sample depths, stratigrap soil engine ring ch cte stic an gro currence.
The stratigraphi tacts sho th bo ng o rep es t t e aoundaries
between s ' ypes; ad al ran iti s ay b m grad al Th soil and groundwater
condition depicted are only for the ecifi date and to t on reported, and therefore, are
not neces arilPs
ee alive of othe oc do tim
At intery s withinhe o ngs, St ndar a tration Test (SPT) sampling was performed
using a 2-richde is ete spl - n sampler and a standard 140-pound hammer.
During th tesm le i ob ained by driving the sampler 18 inches into the soil with a
hammer e-falling in es per stroke. The number of blows required for each 6 inches
' of penetr ion is r orded. The SPT Resistance ("N-value") of the soil is calculated as the
number o s required for the final 12 inches of penetration. The N-value provides a
measure of the relative density of granular soils and the relative consistency of cohesive
soils.
Soil samples were classified in the field and representative portions were placed in air-tight
plastic bags. These soil samples were then returned to our Lynnwood, Washington
laboratory for further examination and testing.
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE TEST SYMBOLS
COHESIONLESS SOILS COHESIVE SOILS %F Percent Fines
Approximate Approximate AL Atterberg Limits: PL = Plastic Limit
' Density N(blows/ft) Relative Density(%) Consistency N(blows/ft) Undrained Shear LL = Liquid Limit
Strength(psf) CBR California Bearing Ratio
Very Loose 0 to 4 0 - 15 Very Soft 0 to 2 <250 CN Consolidation
Loose 4 to 10 15 - 35 Soft 2 to 4 250 - 500 DD Dry Density(pcf)
Medium Dense 10 to 30 35 - 65 Medium Stiff 4 to 8 500 - 1000 DS Direct Shear
Dense 30 to 50 65 - 85 Stiff 8 to 15 1000 - 2000 GS Grain Size Distribution
Very Dense over 50 85 - 100 Very Stiff 15 to 30 2000 - 4000 K Permeability
Hard over 30 1 >4000 MD Moisture/Density Relationship (Proctor)
USCS SOIL CLASSIFICATION SYSTEM MR Resilient Modulus
PID Photoionization Device Reading
MAJOR DIVISIONS GROUP DESCRIPTIONS PP Pocket Penetrometer
Approx.Compressive Strength(tsf)
1 0 GW Well-graded GRAVEL SG Specific Gravity
Coarse Gravel and Clean Gravel � TC Triaxial Com ression
Grained Gravelly Soils (little or no fines) p
• 0 GP Poorly-graded GRAVEL TV Torvane
Soils More than Approx.Shear Strength (tsf)
50%of Coarse Gravel with . GM Silty GRAVEL UC Unconfined Compression
Fraction Retained Fines(appreciable
on No.4 Sieve amount of fines) GC Clayey GRAVEL SAMPLE E SYMBOLS
Sand and Clean Sand SW Well-graded SAND ® 2.0" Split Sp on (SPT)
' Sandy Soils (little or no fines) 40 lb.hammer with 30 in.drop)
More than SP Poorly-graded SAND
50%Retained Shelby Tub
50%or More
on No. of Coarse Sand with SM Silty SAND
OD S lit Spoon with Brass Rings
200 Sieve Fraction Passing Fines(appreciable
Size amount of fines) SC Clayey SAND
No.4 Sieve Sm I Bag ample
Fine Silt ML S Lar Bag (Bulk)Sample
Grained and Liquid Limit
' Less than 50% CL can CLAY Con Run
Soils Clay
QL Orga SILT rganic CLAY Z Non 1�jpoon
trd Penetration Test
(wit sampler)
MH Elas c ILr
50%or More Silt
Liqui Limit
Passing a"aY o% r Mor C Fat GROUNDWATER SYMBOLS
No.200 Sieve Q Groundwater Level (measured at
/ Q Organic SILT/Org nic CLAY
Size // = time of drilling)
' Highl Orga is Soil = Groundwater Level(measured in well or
open hole after water level stabilized)
CO PO ENT DE IN TIO S\ Vj COMPONENT PROPORTIONS
COMPONENT SIZI RA NGE PROPORTION RANGE DESCRIPTIVE TERMS
Boulders Lin
t 2 in
< 5% Clean
' Cobbles o 12 in
Gravel into No 4 . mm) 5 - 12% Slightly(Clayey,Silty,Sandy)
Coarse gravel o in
Fine gravel to No 4(4.5mm)
Sand No.4(4.5 mm)to No.200(0.074 mm) 12 -30% Clayey,Silty,Sandy, Gravelly
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) 30-50% Very(Clayey,Silty,Sandy,Gravelly)
Fine sand No.40(0.42 mm)to No.200(0.074 mm)
Silt and Clay Smaller than No. 200(0.074mm) Components are arranged in order of increasing quantities.
NOTES: Soil classifications presented on exploration logs are based on visual and laboratory
observation in general accordance with ASTM D 2487 and ASTM D 2488. Soil descriptions MOISTURE CONTENT
are presented in the following general order:
DRY Absence of moisture,dusty,
Density/consistency,color,modifier(if any)GROUP NAME,additions to group name(if anyl,moisture content. dry to the touch.
proportion,gradation,and angularity of constituents,additional comments. (GEOLOGIC INTERPRETA 77ON) MOIST Damp but 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
1 complete description of subsurface conditions. soil is below water table.
LEGEND OF TERMS AND
SW 23rd Street Drainage Channel Deepening SYMBOLS USED ON
HMGEOSaENCES INC.
Renton, Washington EXPLORATION LOGS
' PROJECT NO.: 891 9-200 FIGURE: A-1
LEGEND 89192 5/13/98
DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: Track Mounted Mobile, 4-1/4" ID HSA DATE COMPLETED: 6/20/97
SURFACE ELEVATION: 14 t Feet LOGGED BY: David Sowers
N m W
N W U— 1
Qca
v W Q r Standard Penetration Resistance
' - Z u~) c w (140 lb. weight, 30" drop) m
-.1 0 W W w
= co ♦ Blows per foot
Q 0- J y =
F- m g a cc Z
o_ ; W D
Z o
' = O N a 0 7
0 W
0 Q DESCRIPTION (nn (n cm 0 10 20 30 40 50
SP Medium dense, olive brown to gray, poorly 0
SM graded SAND with silt and gravel, moist to
wet. Fine to medium sand.
(FILL) S-1 15-13-8 ♦ '
5 Q _ _ .. _ .. 5
OH Very soft, dark grayish brown, organic SILT,
wet. Interbeds of dark brown peat. S-2 1-1-1 AL
(RECENT ALLUVIUM)
10 ......_..........._. 10
SM Loose, dark gray to very dark gray, silty SAND,
wet. Fine to medium sand.
' 3 -5-3 ♦`
Silt interbeds.
15 ...... ......E.... ` . _ . _ . _ .. 15
ML Soft t med um s iff,v try ark SILT, we
20 ......_......'.............E...... ......E....... _ .. 20
- - - - - - - - - - -
SM Loose, dark r silt SA D, w t. Fine to
mediu san .
L
S-5 1-2-2
Botto of ring at 24 feet.
25 ............ ............ ......€...... . _ .. 25
Groundwater observed at 5 feet below the
ground surface during drilling.
30 0 20 40 60 80 100 30
Water Content M
Plastic Limit 1--0 Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
Ir"MA I SW 23rd Street Drainage Channel Deepening BORING: BH-1
' HWAGEOSCIENCES INC Renton, Washington PAGE: 1 of 1
' PROJECT NO.: 891 9-200 FIGURE: A-2
BORING 89192 10/5198
DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: Track Mounted Mobile, 4-1/4" ID HSA DATE COMPLETED: 6/20/97
SURFACE ELEVATION: 15 t Feet LOGGED BY: David Sowers
1 N w
Q
w U_ o:
v a co Q-C Standard Penetration Resistance
' Z u~i c w 30 in (140 lb. weight, 30" drop) m
0 w w W co o A Blows per foot
w D
' Z o
o LU u DESCRIPTION N}i Q uai a•n O 0o
0 10 20 30 40 50
0 SP Medium dense, olive brown, poorly graded 0
SAND with gravel,moist to wet. Fine to coarse
sand.
(FILL) S-1 12-13-7 GS
i
5 SZ ......_......E......_......E . _ . _ . _ .. 5
OH Very soft, dark grayish brown, organic SILT, S-2 0-1-1
wet. Interbeds of dark brown peat.
jj (RECENT ALLUVIUM)
10 _ . _ .. 10
ML Very soft to medium stiff, very dark gray, SILT
with sand, wet.
3 1 2"-1
1 5 ........... ..........._ . _ . _ .. 15
14-3- F
20 ...... ............ ......s......_ . . _ . . - 20
SM Very I se, a gray silty SA , wet. Fine to
mediu san .
1/18"
Botto of Ing at 24 feet.
25 ...... ......i...... ......i......3...... _ . _ .. 25
Groundwater observed at 5 feet below the
ground surface during drilling.
r
30 0 20 40 60 80 100 30
Water Content M
Plastic Limit 1 0 Liquid Limit
Natural Water Content
1 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.
ir0AA SW 23rd Street Drainage Channel Deepening BORING: BH-2
HWAGEOSCIENCES INC Renton, Washington PAGE: 1 of 1
PROJECT NO.: 891 9-200 FIGURE: A-3
BORING 89192 10/5/98
is
APPENDIX B
' LABORATORY TESTING
' APP ENDIX B
LABORATORY TESTING
HWA personnel performed laboratory tests in general accordance with appropriate ASTM
test methods. Selected soil samples from the exploratory borings were tested to determine
' moisture content, grain size distribution, and plasticity characteristics (Atterberg Limits).
The test procedures are briefly discussed below.
Moisture Content
Laboratory tests were conducted to determine the moistur ontent o ed it
tsamples, in general accordance with ASTM D-221 . Test resul re indicated the
sampled intervals on the boring log in Append' A.
' Grain Size Distribution
Grain size distribution wa dete ned ors ec s ple in eneral accor an with
' ASTM D-42 esu so the a lys s ar pl tt do Figure -1.
Plasticity Cha a eris is
Testing tc det rmi a pl Lst city c ract ics, or At erberg Limits, of a select sample was
determine I in en al a cordar ice ith D-422. Results of this analysis are plotted
on Figure -2, an are sh wn n t propriate boring log in Appendix A.
GRAVEL SAND SILT CLAY
Coarse Fine Coarse Medium Fine
U.S. STANDARD SIEVE SIZES
3/4"
3" 1-1/2" 15/8" 318" #4 #10 #20 #40 #60 #100 #200
100
i 1 1 1 i 1 i 1 1 i
90
80
70
uj
60
} 1 1 i 1 i 1 i 1
L1J 50
z
LL
F—
40
uj
� 30
LVCL
20
10
1 1 1 1 i 1 i i i
0
50 10 5 1 0.5 1 NO.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN ET S
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % C LL PL PI % Gravel % Sand % Fines
• BH-1 S-1 2.5 -4.0 (SP-SM) Olive brown, poorly graded SA with silt and gravel. 8 27.4 65.5 7.1
■ BH-1 S-4 17.5 - 19.0 (ML) Very dark gray, SILT 36 91.5
A BH-2 S-4 17.5 - 19.0 (ML) Very dark gray, SILT with sand. 77.7
GRAIN SIZE
SW 23rd Street Drainage Channel Deepening DISTRIBUTION
HWAGEOSCIENCES INC. Renton, Washington TEST RESULTS
PROJECT NO.: 891 9-200 FIGURE: B-1
HWAGRSZ 89192 5/13/98
� � � i� � � l� l� � � I� I� I� li• � � � � �
60
CL CH
50
CL
X 40
w
Q
Z
•
y- 30
H
U_
I-
Q 20
J ?00"
CL
10
CL-ML I L
0
0 10 20 30 40 50 �"-�-60 7 80 90 100 110
IQUID )
SYMBOL SAMPLE DEPTH (ft) LASSIFICATION % MC LL PL PI % Fines
• BH-1 S-2 7.5 - 9.0 (OH) Dark grayish brown, organic SIL 109 84 52 32
_j
SW 23rd Street Drainage Channel Deepening PLASTICITY CHART
HWAGEOSCIENCES INC. Renton, Washington
PROJECT NO.: 89 1 9-200 FIGURE: B-2
HWAATTB 89192 6/13198
' APPENDIX C
� HCE EXPLORATIONS (1989)
' HAND BORE LOG
DEPTH GROUND MOISTURE CONTENT •/. S
' SOIL DESCRIPTION WATER Blows per ft.*
(feet) a CONDITION
10 20 30 40 50 6070
Soft, gray brown, clayey SILT
1 with grass and rootlets (CL) i
Loose, dark brown silty SAND which _
2 contains peat layers (SMJPT)
-(Peat Bog)
3 Soft, dark brown PEAT (-PT)
' 4 (Peat Bog) 188.5%
5
Soft, dark brown PEAT with some �
�
6 layers of organic silt (-PT/OH) 70 .o/
7
1
Soft, gray, SILT wit
8 sand and or is (M )
(Peat Bo )
9 Soft, dark ra , o g nic clay SILT (OH)
10 ( )ea Bog)
11 Medium censt ra e:�m to 100
fine SA D w tr ce some silt
' 12 (SP-SM) (A uvium)
END OF HOLE
*Penetration resistance
' using 40 lb. hammer - 22" drop
' PROJECT DATE 4-25-89 MOLE NO.
Figure Panther Creek LOGGED 9Y SEG HB-1
8 Renton, WA. ELEVATION 11.5' SHEET
DEPTH 12' 1 of 1
HONG CONSULTING ENGINEERS, INC.
' HAND BORE LOG
IAj DEPTH GROUND MOISTURE CONTENT •/. S
' SOIL DESCRIPTION I WATER
(feet Blows per ft.
) N CONDITION to zo as ao so so 70
' Loose, brown , silty sandy GRAVEL
1 (GW-GM) (Fill )
Soft, dark brown PEAT with layers —
' of organic silt (PT/OH)
2
Soft, dark brown PEAT (PT)
3
(Peat Bog) t
' 4
t
5
' 6 Soft, dark brown PEAT with some
organic silty layers (PT -OH)
t
' 8
9
Medium en ra edium t 100
P-
fine SADfilthtrace to ome it10 (SSM11 i m)
' E 0 H LE
rt i*Pene ra s ce
m0using 4 amer - 22" drop
' PROJECT DATE 4-25-89 MOUE NO.
Figure Panther Creek LOGGED BY SEG HB-2
' 9 Renton , WA. ELEVATION 12.51 SHEET
DEPTH 10, 1 of 1
' HONG CONSULTING ENGINEERS, INC.
' HAND BORE LOG
GROUND MOISTURE CONTENT % S
DEPTH
' SOIL DESCRIPTION � WATER Blows per ft. * •
(feet) 4 CONDITION
v� 10 20 30 40 SO 60 70
' Loose, dark brown organic
topsoil
• 1 �
' Loose, brown fine SAND with
2 trace silt (SP)
' 3 (Alluvium)
i
' 4 1
Medium stiff, gray brown mottled
' 5 Dense, gray fine SAND with some — _ 120/6„
6 silt (SP-SM)
END OF HOLE
*Penetration esis anc
using 4 ha me - 2" dr
1
1
PROJECT DATE 4-25-89 HOLE NO.
Figure Panther Creek LOGGED BY SEG
HB-3
' 10 Renton, WA. ELEVATION 13.5' SHEET
DEPTH 6' 1 of 1
' HONG CONSULTING ENGINEERS, INC.
i