Larsen Short Plat Shoring Comment Response #1.pdfC �
ENGINEERING
May 3, 2019
civil & structural
engineering & planning
Jen Machuga
City of Edmonds Development Services, Engineering Division
Second Floor City Hall
121 5th Avenue N
Edmonds, WA 98020
RE: Application #: PLN20180033
Project Name: Larsen 3-Lot Short Plat - Shoring
Project Address: 15729 75th PL W
Dear Ms. Machuga,
Itemized below is our response to the review comments in the February 13, 2019 letter for the above
referenced project. Our response appears in bold.
Memorandum
1. We recommend clearly stating the shoring walls are permanent and include a design life.
The walls are permanent with a design life of 50 years. The note has been added to the lagging
notes on SH1.1.
2. The geotechnical engineer shall be contacted and provide written concurrence to ensure soldier pile
walls are feasible at the site, design recommendations are developed, and construction
recommendations are provided.
A geotechnical review memo will be submitted with these responses.
3. We recommend following the NCHRP Report 350 "Recommended Procedures for the Safety
Performance Evaluation for Highway Features" considering the walls are located approximately 3-
feet from the edge of roadway used for local traffic.
The road is more of a driveway than a highway. Regardless, a separate guardrail has been added
to the plans. Refer to revised civil plans.
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Larsen Short Plat 17145.15
Comment Response — Engr - Shoring
May 3, 2019
Page 2 of 4
DRAWINGS
SH1.1:
1. Recommend Shaft Installation Plan shop drawings to include construction operation sequence,
proposed equipment, shaft excavation methods, shaft stability methods, soldier pile placement
details, concrete placement details, etc.
The wall requires geotechnical special inspections. We believe their presence of the geotechnical
engineer on site should be sufficient to deem what is acceptable.
2. Incorrect Date
The report date has been revised on the drawings.
3. Remove and replace with appropriate note as shallow foundation recommendations are not
applicable for soldier pile wall. Have geotech provide recommendations.
The note has been removed.
4. Dampproofing is provided to prevent moisture from passing into the interior face of walls, typically
in building applications; not necessary for an exposed soldier pile wall.
The note has been removed.
5. There is no drainage provided for the walls. Lagging is placed with gaps between lagging boards to
allow water seepage and prevent hydrostatic buildup.
The note has been removed.
6. Confirm as these properties are different than what the design calculations call out. However,
douglas fir -larch woods, grade #2 or better, shall be used for permanent lagging as they are more
durable and have a longer lifespan.
The calculations have been revised to reflect the DF-L #2.
7. Add shaft excavation and pile installation to sequence.
The procedures have been added to the notes.
8. Confirm loading, minimum pile embedment, and other design recommendations with the geotech.
Recommendations within the geotechnical report are not for cantilevered soldier pile walls.
Refer to the geotechnical review letter.
250 4th Avenue South, Suite 200
C C Edmonds, WA 98020
ENGINEERING ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Larsen Short Plat 17145.15
Comment Response — Engr -Shoring
May 3, 2019
Page 3 of 4
SH2.1:
1. Guardrails are typically mounted to posts every 6.25; however, in this case it will be every 8'. Is
the spacing adequate for the guardrail beam to resist loads?
Refer to revised plan on sheet SH2.1.
2. Soldier pile shaft may be in conflict with waterline. Suggest shifting wall south several feet.
The waterline has shifted. Refer to revised plan on SH2.1.
3. Finished grade of roadway/driveway is on a 5% grade. Verify the top of wall is adequate.
Refer to the revised finish grade on 2 & 3/SH2.1.
4. Embed lagging 1' to 2' below grade at front of wall to prevent scour or sloughing of backing.
The lagging is now embedded 1'. Refer to revised profile 2/SH2.1.
5. Suggest lagging to extend 12" min. above finished grade.
The lagging extends 1' above finished grade. Refer to revised profile 2/SH2.1.
6. Update bottom of pile elevations. Embed shown is 20' but calculations are 21.2'.
Refer to the revised elevations and revised structural calculations.
SH3.1:
1. Recommend placing guardrail block between pile and guardrail beam to reduce damage to pile
if collision occurs. Details for anchorage of guardrail to pile (i.e. holes to be fabricated in pile)
shall be shown on plans.
A separate guardrail has been added per civil.
2. Guardrails are typically placed at 32" above grade.
A separate guardrail has been added per civil.
3. Recommend extending lagging above finished grade 12" min. to provide curb for debris and
runoff.
Refer to revised detail 1/SH3.1.
4. Recommend adding filter fabric at back of lagging to prevent spillage of soil through lagging
spaces.
250 4th Avenue South, Suite 200
C C Edmonds, WA 98020
ENGINEERING ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Larsen Short Plat 17145.15
Comment Response — Engr - Shoring
There is draining gravel behind the lagging. The filter fabric is not necessary.
May 3, 2019
Page 4 of 4
5. Recommend embedding lagging 1' to 2' below finished grade to prevent scour or sloughing of
fill.
Refer to revised detail 1/SH3.1.
6. Specify minimum bearing length.
Refer to revised detail 2/SH3.1.
CALCULATIONS
1. Confirm loading with the geotech. Recommendations within the geotechnical report are not for
cantilevered soldier pile walls.
Refer to the geotechnical review letter.
2. Six -thousand pound load per IBC is intended for walls along garage floors or ramps (see ASCE 7-
10 Chapter 4). Loading per NCHRP Report 350, TL-1 (13.5 kips) is more appropriate for the
proposed conditions.
A separate guardrail has been added to the plans. Refer to revised civil plans.
3. Permanent lagging is typically designed for the full load and does not include soil arching. A
reduction in the loads to account for soil arching effects may be taken if allowed per the
Geotech.
Refer to the geotechnical review letter.
4. Conflicts with timber properties shown on plans (douglas fir). Recommend not using hem -fir
woods as they do not provide adequate durability for permanent walls in wet conditions.
The structural calculations have been revised to DF-L lagging.
If you have any questions or comments regarding the responses to this review, please do not hesitate to
call.
Sincerely,
CG Engineering
Dennis Titus, PE, SE
Project Manager
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ENGINEERING ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com