Geotechnical Exploration Plan_rev.pdfULT"Im HWA GEOSCIENCES INC.
Geotechnical & Pavement Engineering •Hydrogeology •Geoenvironmental•Inspection &Testing
October 25, 2018
HWA Project No. 2018-146-21
City of Edmonds — Engineering Division
121 5th Avenue N
Edmonds, WA 98020
Attention: Greg Malowicki
Subject: Geotechnical Exploration Plan
Edmonds 2019 Storm Maintenance Project
Edmonds, Washington
Dear Mr. Malowicki:
HWA GeoSciences Inc. (HWA) is planning to conduct ten (10) geotechnical machine drilled
borings in support of new stormwater pipelines along 88th Avenue W, Olympic View Drive and
the utility easement opposite 194th Street SW in Edmonds, Washington. The location of the
project site is shown on the Site Vicinity Map, Figure 1. The ten (10) borings will be completed
in three (3) working days and they will be conducted within the City right of way (ROW). We
have generated this narrative to convey the specifics of our proposed geotechnical explorations
to the City of Edmonds for approval.
SCOPE OF WORK
As part of the exploration program, we propose to advance eight (8) borings drilled to an
anticipated depth of 10 — 12 feet below ground surface (bgs), designated BH-1 through BH-7 and
BH-10, in support of stormwater pipeline improvements along 88th Avenue W and Olympic
View Drive. Two (2) borings, designated BH-8 and BH-9 will be drill to an anticipated depth of
10 feet in support of stormwater pipeline improvements along the utility easement opposite 194th
Street SW. The proposed location of each of these borings is indicated on the Proposed
Exploration Plan, Figure 2. As shown on Figure 2, borings BH-1, BH-3, BH-4, BH-5 and BH-7
will be confined to within the vegetated or landscaped areas beyond the shoulder. BH-2 and BH-
6 will be advanced within the sidewalk and will require partial sidewalk closure and coring of the
paved surface prior to drilling. BH-10 will be advanced within the southbound travel lane and
will require coring of the paved surface prior to drilling; therefore, traffic control during
completion of this boring will require one -lane, two-way traffic control with flaggers. All the
proposed boring locations are subject to minor location changes based on underground utilities
as well as traffic control requirements.
21312 3011 Drive SE
Suite 110
Bothell, WA 98021-7010
Tel: 42.774.0106
Fax: 425.774.2714
www.hwageo.com
October 25, 2018
HWA Project No. 2018-146-21
HWA will provide the required traffic control in conformance with WSDOT regulations and the
Manual of Uniform Traffic Control Devices (MUTCD).
DRILLING PROCEDURE:
Exploratory borings will be advanced by Geologic Drill Explorations of Spokane, Washington,
using a limited access Bobcat track mounted drill rig (Appendix A, Figure A-1) and/or a hand
portable hollow stem auger drill rig (Appendix A, Figure A-2). The drillers will determine which
drill rig to use based on ease of access, safety, field and geologic conditions, and other
restrictions. The borings will be advanced into the ground using the hollow -stem auger drilling
technique. The borehole is drilled by simultaneously rotating and axially advancing the auger
column into the soil. The cutting teeth on the auger break up the formation or fill materials and
convey them upwards along the rotating auger flights. Standard Penetration Test (SPT) sampling
will be performed in the boreholes at desired intervals using a 2-inch outside diameter split -
spoon sampler and a 140-pound manual drop hammer. The soil samples obtained will be
transported to HWA laboratory for further testing. Soil cuttings from the borings will be placed
in steel drums and transported off site for disposal. After each boring reaches target depth, the
borehole will be abandoned using a bentonite grout slurry in accordance with DOE requirements
and any cuttings at the surface will be removed. A geotechnical engineer or a geologist from
HWA will log each exploration and record all pertinent information.
RESTORATION
After each boring reach target depth, the borehole will be abandoned using bentonite grout in
accordance with Washington State Department of Ecology requirements and any cuttings at the
surface will be removed. The borings will be filled with bentonite grout to about 6 inches below
the ground surface. For borings within the vegetated or landscaped areas, the surface will then
be releveled and raked smooth. Any unconsolidated soil directly below the road/sidewalk
section will be compacted using a hand operated slide compactor. Six inches of crushed gravel
will be placed and compacted in the borehole to the base of the existing pavement/sidewalk
section. Borings within paved surfaces will be patched with rapid setting concrete and dyed to
match existing pavement conditions. Saw cutting and hot mix patching are not included in this
restoration scheme.
DURATION OF WORK
We anticipate that drilling the ten (10) proposed boreholes will take three (3) days to complete
with each boring taking between 2 to 3 hours. HWA proposes to drill each boring between the
hours of 8:00 AM and 5:00 PM. HWA will schedule drilling of these explorations once approval
is provided by the City of Edmonds. If required permits are not obtained four days ahead of the
scheduled drilling, HWA would have to reschedule the drilling for a later time. In our
experience, it would take about 2-3 weeks to reschedule drilling dates.
Geotechnical Exploration Plan 2 HWA GeoSciences Inc.
October 25, 2018
HWA Project No. 2018-146-21
TRAFFIC CONTROL PLAN LAYOUT
The completion of all the borings, with the exception of boring BH-10, will not impact the flow
of traffic on 88th Avenue W. Borings BH-2 and BH-6 will required full or partial sidewalk
closure. HWA proposes to utilize caution cones and pedestrian signage along the existing
sidewalk as a means facilitating the sidewalk closure. Boring BH-10 will be advanced within
the southbound travel lane. The proposed traffic -control plan for the one lane closure (boring
BH-8) is presented in Figure 3 (based on WSDOT TC 1 — One -Lane, Two -Way Traffic Control
with Flaggers)
HWA will place traffic cones around the proposed work area during drilling at each location. A
flagger will be provided to guide pedestrians past the work zone where no good pedestrian
detour exists.
O.O
If you have any questions or require additional information, please contact the undersigned at
your earliest convenience at (425) 774-0106.
Sincerely,
HWA GEOSCIENCES INC.
Zakeyo Ngoma, P.E.
Geotechnical Engineer
Attachments:
Figure 1 Site Vicinity Map
Figure 2 Proposed Exploration Plan
Figure 3 WSDOT Traffic Control Plan for One -Lane, Two -Way Traffic Control
with Flaggers (TC 1)
Appendix A Pictures of proposed drilling equipment
Figure A-1. Picture of Mini Track Drill Rig
Figure A-2. Picture of Hand Portable Drill Rig
Geotechnical Exploration Plan 3 HWA GeoSciences Inc.
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BUFFER DATA
LONGITUDINAL BUFFER SPACE = B
SPEED (MPH)
25
30
35
40
45
50
55
60
65
70
LENGTH (fleet}
155 2D0
1 250
305
360
425
495
570
645
730
TRANSPORTABLE ATTENUATOR ROLL AHEAD DISTANCE = R
HOST VEHICLE WEIGHT
9,900 TO 22,DD0 lbs.
HOST VEHICLE WEIGHT
> 22,0D0 lbs.
< 45 MPH
45-55 MPH
> 55 MPH
< 45 MPH
45-55 MPH
> 55 MPH
100'
123'
172'
74'
100'
159
PROTECTIVE VEHICLE (WORK VEHICLE) = R
NO SPECIFIED DISTANCE REQUIRED
x x x x
48' 48'
ONE LANE .
ROAD
AHEAD
48' 48'
48' W204 �• W204A
ROAD BE
WORK PREPARED
AHEAD To STOP
46' 49'
W20-1 W20-70
W20-78 (OPTIONAL IF
40 MPH OR LESS)
LEGEND
� '
d/
FLAGGING STATION
b
TEMPORARY SIGN LOCATION
a
CHANNELVING DEVICES
®
PROTECTIVE VEHICLE
50' TO
300'
SIGN SPACING
= X (1)
RURAL HIGHWAYS
60 165 MPH
800't
RURAL ROADS
45 155 MPH
sw±
RURAL ROADS & URBAN ARTERIALS
35 140 MPH
359t
RURAL ROADS, URBAN ARTERIALS,
25 130 MPH
200't (2)
RESIDENTIAL & BUSINESS DISTRICTS
URBAN STREETS
25 MPH OR LESS
IW± (2)
(1) ALL SPACING MAY BE ADJUSTED TO
ACCOMMODATE
INTERSECTIONS AND DRIVEWAYS.
(2) THIS SPACING MAY BE REDUCED IN
URBAN AREAS TO
FIT
ROADWAY CONDITIONS.
50' TO 100'
6 DEVICE
MIN * I
iiiii
IAfr i.K
o ?I -A
WI0-7B (OPTIONAL F
40 MPH OR LESS)
4P
DE
WPARED
TO STOP
�• 48'
. y2o-7121 ONE LANE
ROAQ
AHEAD
48' 487
5U TO 100' W20-7A W20 4
6 DEVICE
R I a I MIN. I x I x x I x
ONE -LANE, TWO-WAY TRAFFIC CONTROL
WITH FLAGGERS
NOT TO SCALE
u I�if1
HWAGEOSCIENCES INC.
48'
ROAD
WORK
AHEAD
48-
W2D-1
CHIANNELIZAT10N DEVICE
SPACING FEE
MPH
TAPER
TANGENT
MU55
10 TO 20
80
3W5 10 TO 20 60
25M 110 TO 20 1 40
NOTES
1• ALL SIGNS ARE BLACK ON ORANGE.
2. EXTENDING THE CHANNELIZING DEVICE TAPER ACROSS
SHOULDER IS RECOMMENDED.
3. NIGHT WORK REQUIRES ADDITIONAL ROADWAY LIGHTING AT
FLAGGING STATIONS. SEE THE STANDARD SPECIFICATIONS
FOR ADDITIONAL DETAILS.
4. SEE SPECIAL PROVISK)W FOR WORK HOUR RESTRICTIONS,
FIGURE NO.
3
'ROJECT NO.
2018-146-21
Appendix A
Pictures of Proposed Drilling Equipment
October 25, 2018
HWA Project No. 2018-146-21
Figure A-1: Picture of Mini Track Bobcat Mounted Drill Rig
A ---
Figure A-2: Picture of Hand Portable Drill Rig
Geotechnical Exploration Plan A-1 HWA GeoSciences Inc.