HomeMy WebLinkAbout20000669E005-010
Kirkland | Tacoma | Mount Vernon
425-827-7701 | www.aesgeo.com
September 27, 2022
Project No. 20000669E005
Renton School District No. 403
7812 South 124th Street
Seattle, Washington 98178
Attention: Mr. Stewart Shusterman
Subject: Geotechnical Recommendations Addendum Report
Lindbergh High School Frontage Improvements
16426 128th Avenue SE
Renton, Washington
References: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report
Lindbergh High School Additions
16426 128th Avenue SE
Renton, Washington
Dated February 7, 2022
Lindbergh High School Modernization and Additions
Permit Resubmittal 90% CD
Prepared by Bassetti Architects
Dated June 10, 2022
Dear Mr. Shusterman:
As requested, this report presents an addendum to our previous geotechnical report to provide
recommendations for the proposed frontage improvements at the Lindbergh High School project
in Renton, Washington (Figure 1). This work represents a continuation of our participation on the
project, which has included completion of subsurface explorations, preparation of geotechnical
engineering reports, consultation throughout the design process, and geotechnical construction
observations of work completed to date. This scope of work was based on conversations with
you and the design team, the referenced plan set, and on our knowledge of the site gained
through our participation on several previous projects on campus.
Lindbergh High School Frontage Improvements Geotechnical Recommendations
Renton, Washington Addendum Report
September 27, 2022 ASSOCIATED EARTH SCIENCES, INC.
KAM/ld - 20000669E001-010 Page 2
SITE AND PROJECT DESCRIPTION
The project site is that of the Lindbergh High School campus. Topography of the project vicinity
is characterized by an upland plateau with gentle to moderate slopes.
Previous subsurface explorations onsite by AESI generally encountered surficial loose existing fill
typically up to about 10 feet thick, underlain by very dense lodgement till. The new exploration
borings completed for this task were generally consistent with our previous subsurface
explorations onsite for earlier projects.
Based on the referenced plan set, we understand that the 128th Avenue SE frontage
improvements associated with the project will include:
• Approximately 300 lineal feet of new sidewalk along the east shoulder of 128th Avenue
SE;
• 9 new luminaires along the 128th Avenue SE project frontage;
• New crosswalk ramps at SE 166th Street and SE 176th Street;
• A 2-inch deep asphalt grind and overlay on the northbound lane of 128th Avenue SE
extending approximately 1,100 feet along the entire school property frontage.
The purpose of our work was to provide geotechnical design recommendations for the proposed
frontage improvements. We anticipate that the proposed new luminaires will be the primary
structures for which the City of Renton desires geotechnical engineering input. Our geotechnical
recommendations for design of new sidewalk and curb are based on explorations at proposed
luminaire locations. We do not anticipate that geotechnical input will be needed for asphalt
paving resurfacing.
SUBSURFACE EXPLORATION
Our field study for this task included drilling ten hollow-stem auger exploration borings to obtain
subsurface information about the site (EB-1-22 through EB-10-22). The various types of
sediments, as well as the depths where characteristics of the sediments changed, are indicated
on the exploration logs. The depths indicated on the logs where conditions changed may
represent gradational variations between sediment types in the field. The explorations were
approximately located in the field relative to known site features. The approximate locations of
new explorations as well as previous explorations on campus are shown on Figure 2. Logs of new
explorations are attached with this report. Copies of previous exploration logs are available on
request but are not attached.
The conclusions and recommendations presented in this report are based, in part, on the
subsurface conditions encountered in our explorations. The locations, depths, and number of
Lindbergh High School Frontage Improvements Geotechnical Recommendations
Renton, Washington Addendum Report
September 27, 2022 ASSOCIATED EARTH SCIENCES, INC.
KAM/ld - 20000669E001-010 Page 3
explorations were selected within site and budgetary constraints. It should be noted that
subsurface conditions differing from those depicted on the logs may be present at the site due
to the random nature of deposition and the alteration of topography by past grading and/or
filling. The nature and extent of any variations beyond the field exploration may not become fully
evident until construction. If variations are observed at that time, it may be necessary to
re-evaluate specific recommendations in this report and make appropriate changes.
Exploration Borings
Ten supplementary exploration borings were completed using a limited-access, rubber
track-mounted, hollow-stem auger drilling rig under subcontract to AESI. During the drilling
process samples were generally obtained at 2.5-foot-depth intervals. The borings were
continuously observed and logged by a geologist from our firm. The exploration logs attached
are based on the field logs, drilling action, and inspection of the samples secured.
During drilling, disturbed but representative samples were obtained using the Standard
Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This
test and sampling method consists of driving a standard, 2-inch, outside-diameter, split-barrel
sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of
30 inches. The number of blows for each 6-inch interval is recorded and the number of blows
required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance
(“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is
recorded as the number of blows for the corresponding inches of penetration. The resistance, or
N-value, provides a measure of the relative density of granular soils or the relative consistency of
cohesive soils; these values are plotted on the attached exploration boring logs.
The samples obtained from the split-barrel sampler were classified in the field by a geologist from
our firm and representative portions placed in watertight containers. The samples were then
transported to our laboratory for further visual classification, as described below.
SUBSURFACE CONDITIONS
Stratigraphy
The subsurface explorations summary that follows is limited to supplementary explorations
completed in support of currently proposed frontage improvements. Subsurface conditions were
inferred from the field explorations accomplished for this study and previous studies, visual
reconnaissance of the site, and review of selected applicable geologic literature.
As shown on the exploration logs, the overall stratigraphic sequence observed in our explorations
included fill underlain by lodgement till sediments. The following section presents more detailed
subsurface information on the sediment types encountered at the site.
Lindbergh High School Frontage Improvements Geotechnical Recommendations
Renton, Washington Addendum Report
September 27, 2022 ASSOCIATED EARTH SCIENCES, INC.
KAM/ld - 20000669E001-010 Page 4
Fill
Nine of our exploration borings for this task encountered existing fill of variable thickness. The fill
was generally a loose to dense, brown, silty fine sand. Observed fill depths were generally 2 to
6 feet.
Vashon Lodgement Till
Underlying the fill, all explorations encountered a diamict of dense to very dense, unsorted,
brownish gray, silty fine sand to sandy silt, with trace coarse sand and gravel interpreted as
Vashon lodgement till. The Vashon lodgement till was deposited directly from basal, debris-laden
glacial ice during the Vashon Stade of the Fraser Glaciation, approximately 12,500 to 15,000 years
ago. The high relative density characteristic of the Vashon lodgement till is due to its
consolidation by the massive weight of the glacial ice from which it was deposited. Lodgement
till is suitable for support of structural loads when prepared as recommended in our referenced
report.
Regional Geologic Mapping Review
We reviewed a regional geologic map (D.R. Mullineaux, 1965, Geologic Map of the Renton
Quadrangle, King County, Washington: U.S. Geological Survey, Geologic Quadrangle Map
GQ-405, 1:24,000). The referenced map indicates that the site is expected to be underlain at
shallow depths by Vashon lodgement till. Our on-site explorations and interpretations are
generally consistent with the conditions depicted on the referenced published map.
Hydrology
No groundwater was encountered in the new exploration borings at the time of exploration. The
explorations for this study occurred in late August when groundwater levels are typically at
seasonal lows. The duration and quantity of perched seepage encountered at the time of
construction will largely depend on the soil grain-size distribution, topography, seasonal
precipitation, on- and off-site land usage, and other factors.
DESIGN RECOMMENDATIONS
Our explorations indicate that, from a geotechnical engineering standpoint, the proposed
frontage improvements are feasible if the recommendations in our previous geotechnical report
and in this addendum are implemented. The above-referenced geotechnical report provides
recommendations for site preparation, grading, types of suitable foundations and floors,
allowable foundation soil bearing pressure, anticipated foundation and floor settlement,
drainage considerations, and infiltration feasibility. We recommend that these recommendations
be used in design and construction of the proposed sidewalks and curbs along the 128th Avenue
SE frontage.
Lindbergh High School Frontage Improvements Geotechnical Recommendations
Renton, Washington Addendum Report
September 27, 2022 ASSOCIATED EARTH SCIENCES, INC.
KAM/ld - 20000669E001-010 Page 5
We recommend the proposed luminaires and smaller structures such as pedestrian push buttons
and strobes along 128th Avenue SE be supported by drilled shaft foundations with sufficient
embedment depth to provide the necessary lateral resistance at each pole site. Frontage
improvement elements, Washington State Department of Transportation (WSDOT) Standard
Plan references, and geotechnical design parameters are summarized below.
Luminaire and Accessory Structure Foundation Recommendations
The soils observed along the 128th Avenue SE frontage varied and included loose to dense fill and
dense to very dense lodgement till. The standard penetration resistance at these locations varied.
We recommend using the following allowable lateral bearing pressures for the noted locations,
based on Table 17.2 of the WSDOT Geotechnical Design Manual and SPT N-Values. The allowable
lateral bearing pressure values were determined based on the use of standard 8-foot-deep
foundations with the exception of EB-10 which was determined based on the use of 4-foot-deep
foundations. Foundations for luminaires should be designed and constructed in accordance with
WSDOT Standard Plan J-28.30-03. Foundations for smaller accessory poles should be designed in
accordance with WSDOT Standard Plan J-21.10-04:
Recommended Lateral Bearing Capacity
Arterial Luminaire and Push-Button Foundations 128th Avenue SE Frontage
Approximate
Station AESI Exploration
Recommended Allowable Lateral
Bearing Pressure (psf)*
13+25 EB-1 4,500
13+75 EB-2 4,500
14+00 EB-3 4,500
15+25 EB-4 3,500
15+75 EB-5 3,500
16+50 EB-6 4,500
17+00 EB-7 4,500
17+75 EB-8 4,500
18+25 EB-9 4,500
19+50 EB-10 3,500
* Washington State Department of Transportation Geotechnical Design Manual, Table 17.2
psf = pounds per square foot
Lindbergh High School Frontage Improvements Geotechnical Recommendations
Renton, Washington Addendum Report
September 27, 2022 ASSOCIATED EARTH SCIENCES, INC.
KAM/ld - 20000669E001-010 Page 6
CONSTRUCTION RECOMMENDATIONS
We recommend that AESI be allowed to observe installation of foundations for frontage
improvement items included in this report to confirm that subsurface conditions encountered at
the time of construction are consistent with our observations during the design phase.
CLOSURE
We have enjoyed working with you on this study and are confident that these recommendations
will aid in the successful completion of your project. If you should have any questions or require
further assistance, please do not hesitate to call.
Sincerely,
ASSOCIATED EARTH SCIENCES, INC.
Kirkland, Washington
______________________________
Kristen A. Marohl, G.I.T.
Senior Staff Geologist
______________________________
Bruce W. Guenzler, L.E.G. Kurt D. Merriman, P.E.
Principal Geologist Senior Principal Engineer
Attachments: Figure 1: Vicinity Map
Figure 2: Site and Exploration Plan
Exploration Logs
KING COUNTY
KING COUNTY
RENTON
PROJ NO.
NOTE: BLACK AND WHITE
REPRODUCTION OF THIS COLORORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION DATE:FIGURE:
±\\kirkfile2\GIS\GIS_Projects\aY00post0716\000669 Lindbergh HS\aprx\20000669E005 F1 VM_Lindbergh.aprx | 20000669E005 F1 VM_Lindbergh | 12/8/2021 9:38 AMDATA SOURCES / REFERENCES:
USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013
KING CO: STREETS, CITY LIMITS, PARCELS, PARKS 3/20
LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE
0 2000
Feet
VICINITY MAP
LINDBERGH HS IMPROVEMENTS
RENTON, WASHINGTON
20000669E005 12/21 1
King County
¥
¥
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¬«
¬«169
!(
SITE
0
2.5
5
7.5
10
12.5
15
17.5
1
2
3
Grass Surfacing
Fill
Slightly moist, brown, silty, fine SAND, trace coarse sand, some gravel; trace
rootlets (SM).
Weathered Vashon Lodgement Till
Moist, grayish brown, silty, fine SAND to sandy, SILT, trace gravel (SM-ML).
Moist, grayish brown, sandy, SILT, trace gravel; sand is predominately fine
with trace coarse; massive; diamict (ML).
No groundwater encountered.
181326
212739
212519
39
66
44
Associated Earth Sciences, Inc.
Exploration Boring EB-1
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):9Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»402Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
3
4
Grass Surfacing
Fill
No recovery; driller notes bouncing on gravel.
Slightly moist, silty, fine SAND, trace coarse sand, some gravel (SM).
Vashon Lodgement TillDrill action increases at 6.5 feet.
Moist, grayish brown, silty, fine SAND to sandy, SILT, trace coarse sand,
trace gravel; massive; diamict (SM-ML).
As above.
No groundwater encountered.
50/4"
471929
141822
112950/6"
50/4"
48
40
50/6"
Associated Earth Sciences, Inc.
Exploration Boring EB-2
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):11.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»405Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
3
4
Grass Surfacing
Fill
Moist, dark brown, silty, fine SAND, trace gravel; contains frequent rootlets
(SM).
Vashon Lodgement Till
Moist, grayish brown with oxidized staining, silty, fine SAND to sandy, SILT,
trace coarse sand, trace gravel; massive; diamict (SM-ML).
As above; no staining.
As above.
No groundwater encountered.
324
114129
50/6"
50/6"
6
70
50/6"
50/6"
Associated Earth Sciences, Inc.
Exploration Boring EB-3
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):10.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»408Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
3
4
Grass Surfacing
Fill
Moist, dark brown, silty, fine SAND, trace gravel; contains frequent rootlets
(SM).
Upper 8 inches: Moist, dark brown, sandy, SILT, some gravel; contains
occasional rootlets (ML).
Vashon Lodgement TillLower 10 inches: Moist, grayish brown with oxidized staining, silty, fine
SAND to sandy, SILT, trace coarse sand, trace gravel; massive; diamict (SM-
ML).
As above; no staining.
As above.
No groundwater encountered.
1684
229
222433
50/4"
12
11
57
50/4"
Associated Earth Sciences, Inc.
Exploration Boring EB-4
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):10.3Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»415Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
Grass Surfacing
Fill
Vashon Lodgement Till
Moist, grayish brown, silty, fine SAND to sandy, SILT, trace coarse sand,
trace gravel; massive; diamict (SM-ML).
Refusal due to gravel.
No groundwater encountered.
111421
35
Associated Earth Sciences, Inc.
Exploration Boring EB-5
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):4Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»421Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1 Grass Surfacing
FillUpper 10 inches: Slightly moist, brown, silty, fine SAND, trace gravel (SM).
Weathered Vashon Lodgement TillLower 8 inches: Moist, grayish brown with oxidized staining, silty, fine
SAND to sandy, SILT, trace coarse sand, trace gravel; massive; diamict (SM-
ML).Refusal at 1.5 feet.
No groundwater encountered.
71336
49
Associated Earth Sciences, Inc.
Exploration Boring EB-6
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):1.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»426Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
Weathered Vashon Lodgement TillSlightly moist, brown, silty, fine SAND, some gravel; rootlets in upper 6
inches; poor recovery (SM)
No recovery.
No groundwater encountered.
71115
50/4"
26
50/4"
Associated Earth Sciences, Inc.
Exploration Boring EB-7
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):2.8Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»428Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
Grass/FillMoist, dark brown, silty, fine SAND, trace gravel; contains occasional
rootlets and organic fragments (SM)
Vashon Lodgement Till
Moist, grayish brown, silty, fine SAND to sandy, SILT, trace coarse sand,
trace gravel; massive; diamict (SM-ML).
No groundwater encountered.
72833
50/6"
61
50/6"
Associated Earth Sciences, Inc.
Exploration Boring EB-8
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):3Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»429Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
1
2
3
Grass/FillSlightly moist, brown, silty, fine SAND, trace coarse sand; diamict; massive
(SM)
As above; contains fragments of debris.
Vashon Lodgement Till
Moist, grayish brown, silty, fine SAND, trace coarse sand, trace gravel;
massive; diamict (SM).
No groundwater encountered.
142727
4814
192736
54
22
63
Associated Earth Sciences, Inc.
Exploration Boring EB-9
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):6.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»430Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1
0
2.5
5
7.5
10
12.5
15
17.5
2
3
Grass/Fill
Slightly moist, light brown, sandy, SILT, trace coarse sand (ML).
Vashon Lodgement TillDrill action increases.
Moist, grayish brown with oxidized staining, silty, fine SAND to sandy, SILT,
trace coarse sand, trace gravel; massive; diamict (SM-ML).
No groundwater encountered.
4815
3950/6"
23
50/6"
Associated Earth Sciences, Inc.
Exploration Boring EB-10
Lindbergh High School Improvements 1Renton, WA Start Date:8/31/22 Logged By:KAM20000669E001Ending Date:8/31/22 Approved By:CMM
Driller/Equipment:Geologic Drill Partners/Mini Tracked RigTotal Depth (ft):6Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»433Hole Diameter (in):6 Datum:NAVD88Groundwater Depth ATD (ft):Not Encountered Groundwater Depth Post Drilling (ft) (Date): ()Depth (ft)Sample TypeSample% RecoveryGraphic SymbolDescription
Water LevelBlows/6"Blows/Foot
10 20 30 40 50+Other Tests20000669E0019/22/2022Sheet: 1 of 1