HomeMy WebLinkAboutGeoTech Report for MEP2008-00057;SHR2008-00024 - GEO Geological Review - 10/24/2008 Mason County Review Checklist
For a Geotechnical Report
Instructions:
This checklist is intended to assist Staff in the review of a Geotechnical Report. The Geotechnical Report
is reviewed for completeness with respect to the Resource Ordinance. If an item is found to be not
applicable, the Report should explain the basis for the conclusion. The Report is also reviewed for clarity
and consistency. If the drawings, discussion, or recommendations are not understandable, they should be
clarified. If they do not appear internally consistent or consistent with the application or observations on
site, this needs to be corrected or explained. If resolution is not achieved with the author, staff should
refer the case to the Planning Manager or Director.
Applicant's Name: Long Live the Kings
Permit#MEP2008-00057; SHR2008-00024 Parcel#32330-51-47003
Date(s)of the Document(s) reviewed: Geotechnical Report 10/24/08
(1) (a)A discussion of general geologic conditions in the vicinity of the proposed development,
OK? Yes Comment: Page 3
(b) A discussion of specific soil types
OK? Yes Comment: Page 3
(c) A discussion of ground water conditions
OK? Yes Comment: Page 3
(d) A discussion of the upslope geomorphology
OK? Yes Comment: Page 3
(e) A discussion of the location of upland waterbodies and wetlands
OK? Yes Comment: Page 3
(f) A discussion of history of landslide activity in the activity in the vicinity, as available in the
referenced maps and records
OK? Yes Comment: Page 3
(2) A site plan which identifies the important development and geologic features.
OK? Yes Comment: Attachment 1 —Topo Map
(3) Locations and logs of exploratory holes or probes.
OK? Yes Comment: Bedrock and till are exposed—not necessary
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacks shall be delineated (top, both sides, and toe) on a geologic map of the site.
OK? Yes Comment: Attachment 1
(5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and
which incorporates the details of proposed grade changes.
OK? Yes Comment: Elevation view(Section 9-9) of Attachment 4
(6) A description and results of slope stability analyses performed for both static and seismic loading
conditions. Analysis should examine worst case failures. The analysis should include the
Simplified Bishop's Method of Circles. The minimum static safety factor is 1.5, the minimum
seismic safety factor is 1.1. and the quasi-static analysis coefficients should be a value of 0.15.
OK? Yes Comment: Pages 4-5
(7) (a)Appropriate restrictions on placement of drainage features
OK? Yes Comment: Page 5
(b) Appropriate restrictions on placement of septic drain fields
OK? Yes Comment: Page 5
(c) Appropriate restrictions on placement of compacted fills and footings
OK? Yes Comment: Page 5
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other
slopes on the property.
Page 1 of 2 Form Effective June 2008
OK? Yes Comment: Page 5
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
other slopes on the property.
OK? Yes Comment: Page 5
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically
identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the
method of vegetation removal.
OK? Yes Comment: Page 6
(9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the specific mitigating measures to be implemented during construction to protect the
slope from erosion, landslides and harmful construction methods.
OK? Yes Comment: Page 6
(10) An analysis of both on-site and off-site impacts of the proposed development.
OK? Yes Comment: Pages 6-7
(11) Specifications of final development conditions such as, vegetative management, drainage,
erosion control, and buffer widths.
OK? Yes Comment: Page 7
(12) Recommendations for the preparation of structural mitigation or details of other proposed
mitigation.
OK? Yes Comment: Page 7-8
(13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location
and nature of existing and proposed development on the site.
OK? Yes Comment: Attachment 3
Are the Documents signed and stamped? Yes
Type and #of License: Professional Engineer; 12002
If not approved, what is the next action/recommendation for further action?
Reviewed by Tammi Wright on 2/4/09
Time spent in review:
SECOND REVIEW/UPDATE:
Reviewed by on
Time spent in second review:
THIRD REVIEW/ UPDATE:
Reviewed by on
Time spent in third review:
Disclaimer: Mason County does not certify the quality of the work done in this Geological Report.
Page 2 of 2 Form Effective June 2008
Mason County Department of Community Development
Submittal Checklist For a Geotechnical Report
Instructions:
This checklist must be submitted with a Geotechnical Report and completed, signed, and stamped by the
licensed professional(s)who prepared the Geotechnical Report for review by Mason County pursuant to
the Mason County Resource Ordinance. If an item found to be not applicable, the report should explain
the basis for the conclusion.
Applicant/Owner L ov%g Lu c ±h t ( IDtit�) E; Parcel# 3 Z.3 3 0 -s l- 47 003
Site Address L % w c L.11\1 wKt� y)
(1) (a)A discussion of general aeblogic conditions in the vicinity of the proposed development,
Located on page(s) ti
(b) A discussion of specific soil types
Located on page(s) lt 3
(c) A discussion of ground water conditions
Located on page(s) 'h' 3
(d) A discussion of the upslope geomorphology
Located on page(s) .
(e) A discussion of the location of upland waterbodies and wetlands
Located on page(s)
(f) A discussion of history of landslide activity in the activity in the vicinity, as available in the
referenced maps and records
Located on page(s) ii,,4�
(2) A site plan which identifies the important development-and geologic features.
Located onMap(s) Greo\o��� -T'bo-o ���� ,-� �f> e,R 4-
(3) Locations and logs of exploratory holes or probes.
Located on Map(s) N o N e cesS�� 3eA pro c�
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacks shall be delineated(top-, both sides, and toe)on a geologic map of the site.
Located on Map(s) Geo(o-a(c,)Tblan arc p
(5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and
which incorporates the detai s of pro osed grade changes. ,
Located on Map(s) 1 I Cyat-t-ot, L) �w ( S e —1 U , �j--9) o�
(6) A description and results of slope stability analyses performed for both static and seismic loading
conditions.Analysis should examine worst case failures. The analysis should include the
Simplified Bishop's Method of Circles.The minimum static safety factor is 1.5, the minimum
seismic safety factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15.
Located on page(s) 14-4-
(7) (a)Appropriate restrictions on placement of drainage features
Located on page(s)_It- 5 :� +-' (9
(b) Appropriate restrictions ns on placement of septic drain fields
Located on page(s) F. i:jrr-/,,
(c) Appropriate restrictions on placement of compacted fills and footings
Located on page(s) r,-
Page 1 of 2 Form Effective June 2008
Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report.
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other
slopes on the property.
Located on page(s)
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
other slopes on the property.
Located on page(s) -It
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically
identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the
method of vegetation removal.
Located on page(s) -tr- L
(9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the specific mitigating measures to be implemented during construction to protect the
slope from erosion, landslides and harmful construction methods.
Located on page(s) b
(10) An analysis of both on-site and off-site impacts of the proposed development.
Located on page(s) to —7
(11) Specifications of final development conditions such as, vegetative management, drainage,
erosion control, and buffer widths.
Located on page(s) 1:"'- -
(12) Recommendations for the preparation of structural mitigation or details of other proposed
mitigation. ^
Located on page(s)
(13) A site map drawn to scale showing the property.boundaries, scale,.north arrow, and the location
and nature of existing and proposed development on t e site. 1 1 I
Located on Map(s) 1n Mat v el ,
I, f
hereby certify under penalty of
perjury th am a civil a ineer I' se in the State of Washington with specialized knowledge of
geotechnical/geological engine oror a geologist or engineering geologist licensed in the State of
Washington with special knowle a of the local conditions. I also certify that the Geotechnical
Report, dated Q c_ 'Z� 2®D�and entitled P l O O 4 DAP ,;;i 1 c_ �Z @,,4-o vwv�m'v-�
I<a IL 0 V meets all the requirements of the Mason
County Resource Ordinance, Land tide Hazard Section, is complete and true, that the assessment
demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the
included geotechnical design recommendations, and that all hazards are mitigated in such a manner as
to prevent harm to property and public health and safety. (Signature and Stamp)
09 c
O r*+
. 2 J
1STE
SS��NAL ENG
EXPIRES 1-9-(1O 1
Page 2 of 2 Form Effective June 2008
Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report.
MARTIG ENGINEERING
P.O. Box 11850
Olympia, WA 98508-1850
(360) 754-9687
Fax (360) 705-0789
October 24, 2008
Mason County
Department of Community Development
426 W. Cedar
P.O. Box 578
Shelton, WA 98584
Attn: Tammi Wright, Land Use Planner
Re: Geotechnical Report Compliance for August/September 2008 Work to Repair
Damages Associated with the December 2007 Floods, including: the removal
of damaging sediment; making necessary Lilliwaup Hatchery repairs; and
installing a Flood-Flow Diversion Berm.
* Property Owner: Long Live The Kings, Lilliwaup Hatchery. (360) 877-6960
600 N Lilliwaup Street
P.O. Box 205
Lilliwaup, WA 98555
Attn: Joy Waltermire
* Site Location: Lots 3 & 4 of Block 47 of Lilliwaup Falls.
Travel north on SR 101 to Lilliwaup, Washington from Shelton.
Take left onto N Lilliwaup Street at head of Lilliwaup Bay of Hood
Canal. Proceed to northerly dead end of Street and turn right,
passing thru large gate and over bridge to east side of Lilliwaup
Creek. Veer right to Hatchery Site.
* Tax Parcel Nos.: 32330-51-47003
* Mason County: Sec. 19, Township 23 N, Range 03 W;
* Proposal: Remove damaging flood deposited sediments from the Lilliwaup
Creek stream regime and repair damages to the Lilliwaup Hatchery
Including;
(i) Reconstruct sediment/treatment pond;
(ii) Reconstruct spawning channel;
(iii) Place a Flood-Flow Diversion Berm; and
(iv) Finish placing Rip-Rap at the NE Bridge Abutment.
1
Dear Ms. Wright:
I, Kenneth W. Martig, Jr., PE, of Martig Engineering have completed my engineering
investigations regarding the Geotechnical Review requirements associated with the
above referenced property, and am including our findings within this Geotechnical
Report.
As a result of our investigations, outlined within this Report, we can affirm that all
potential Landslide Hazards have been overcome in such a manner as to prevent harm
to property and no significant Environmental Impacts will result as a result of this as
outlined within this Report and its attachments.
PROPOSED PROJECT (Emergency)
The "Action" being covered by this Geotechnical Report involves the correction of
problems associated with the severe flood damages to both the Lilliwaup Creek
stream regime and the Lilliwaup Hatchery from the December 2007 heavy rains.
This involves removing damaging flood deposited sediments from the Lilliwaup Creek
stream regime and repairing damages done to the Lilliwaup Hatchery, Including;
(i) Reconstruct sediment/treatment pond;
(ii) Reconstruct spawning channel;
(iii) Place a Flood-Flow Diversion Berm; and
(iv) Finish placing Rip-Rap at the NE Bridge Abutment.
SUMMARY
The above described Action has been completed, in accordance with the prepared
Plans and Specifications that allowed the County and State to issue permission to
proceed with the outlined work.
The Landslide Hazard Area steep slopes within 300-feet of the completed work are
stable. They have been historically stable and the completed work was accomplished to
remove conditions that could destabilize these prior existing stable steep slopes.
2
GEOTECHNICAL REPORT
The following discussion summarizes our: Site Investigations; Research of Site
Conditions; Analyses; and Conclusions.
1. Geologic conditions, soils types, groundwater conditions, upslope geomorphology.
Upland water bodies and history of landslides:
The attached Geologic/Topographic Map and Mason County Soils Map show the
geologic conditions and upslope geomorphology of the site.
The Mason County Soils Map shows that the potentially hazardous steep slopes
within 300-feet of the Action are (Rc) Rough mountainous land, comprised of
Hoodsport soil material. The dominant geologic structural stability of these steep
mountainous soil slopes is due to the presence of the strongly cemented dense till
(a dense cemented mixture of gravel, sand & cobbles), inherent within the
Hoodsport soils series. These slopes have been and remain stable.
Lilliwaup Creek, Beardsley Creek, and two small springs fed unnamed streams flow
thru the Action area. They cause a shallow surface water condition to exist only
within the flat 5% to 15% slope area where the Lilliwaup Hatchery exists. This
condition poses no problem and does not induce any slope instability.
No upland bodies of water or wetlands influence the stability of the subject steep
slopes. Lilliwaup Creek, Beardsley Creek and the two small streams drain the
surrounding slopes such that no nearby upland bodies of standing water exist.
No landslides have occurred within 300-feet of the Action. These steep slopes are
stable. The detrimental sandy gravelly cobbley sediments removed from the
Lilliwaup Creek regime came from failed saturated steeper sloping ravines higher up
in the watersheds of Lilliwaup and Beardsley creeks.
2. Site Plan showing Action and Geologic Features:
The attached Geologic/Topographic Map shows the above described Action (work
completed) and the important Geologic Features (the steep slopes ranging from
22% to 67%).
3. Exploratory Holes or Probes
All work completed was accomplished on land areas located at the base of the
surrounding subject steeper slopes. Therefore, no holes or probes were necessary,
3
since the work would not impact the existing steep slopes.
Furthermore, the examination of historic stereo aerial photographs and visually
occurring natural bedrock and Till outcroppings confirmed the presence of soil types
that can maintain stable steep slopes of 22% to 67% (which they do here).
Therefore, no holes or probing was necessary.
4. Land area of Action, boundaries of potential hazard areas, and associated buffers:
The attached Geologic/Topographic Map shows the boundaries of the potentially
hazardous steep slopes. Because the above described action is Regional in nature,
Tax Parcel Boundaries were not shown here (for clarity , showing the large Action
area superimposed upon the land Topography that depicts the steep slopes).
Due to the scale of the Map and the fact that we are working within the 17.01.100
D 6.a specified 50-foot Buffer, we do not show this Buffer on the Map. Obviously, it
lies at the end of the 300-vector lines delineating the Potentially Hazardous Steep
Slope Area.
5. Cross Section showing grade changes and subsurface profile, where applicable:
Nine Cross Sections were made showing elevation views to help define the
sediment removal work outlined upon Site Plan 1 of 2. A reduced 1" = 100' Site
Plan (1 of 2) is the third attachment to this Report.
We are including only Cross Section 9 — 9 within this Geotechnical Report since it
shows the elements of the Lilliwaup Hatchery restoration work, see the fourth
attachment.
6. Description and results of slope stability analysis:
All potentially hazardous steep slopes within 300-feet of the Action were found to be
stable, with no evidence of surface water erosion, undercutting, or earthquake
induced cracks or displacements.
These surrounding steep slopes remain stable, due to their soil type. Bedrock and
dense cemented Till, with little to no loose granular overburden, make up these
slopes.
Historic Stereo Aerial Photographs were analyzed for signs of slope instability. No
signs of instability or earthquake induced ground movement were found.
Since the stability of the Potentially Hazardous steep slopes is governed by the
4
Bedrock and Hoodsport series Till soil, no calculations were necessary to support
our finding: "that all Potentially Hazardous steep slopes are and have been stable,
and will remain stable since the Action did nothing to alter there condition.
It is our professional opinion that the use of the "Simplified Bishop's Method of
Circles" is not productive with these soils. However, we can evaluate the degree of
protection by comparing the surrounding Potentially Hazardous 67% slopes with the
Published Angle of Repose for Hoodsport Till.
Till, Cemented Sands and Gravels can Stand Vertical, and that Compacted Angular
Gravels have a 200% natural, stable slope. Since the Natural angle of Repose is
200% to near vertical, and the Potentially Hazardous Steep Slopes are as high as
67%, the Stability Factor of Safety is essentially 3.0, well above that required by
Ordinance.
In terms of Seismic Stability the subject property has remained stable after
experiencing over 20 quakes greater than 5.0 during the 42-year Period from 1928
thru 1970, including a 7.1 Olympia quake in 1949 and a 6.5 Tacoma quake in 1965
where significant damages occurred around Puget Sound In fact, the 1965 damages
were more severe than those of the 2001 6.8 Nisqually quake (Data from US
Earthquakes, USD of Commerce, Coast and Geodetic Survey). It is our professional
judgment that these Natural Quakes, coupled with knowledge of the technical
characteristics of the Till soil, demonstrate that Seismic Stability exists at this site.
No indication of slope movement or failure that can be found associated with these
earthquakes, as great in magnitude as that required to be modeled.
7. Appropriate development restrictions and any recommended buffers or setbacks:
No Action items involve the need for septic, water drainage, footing etc..
The only development item associated with this Action involves the placement of the
new Flood-Flow Diversion Berm. All other work associated with this Action either
removes deleterious sediment or restores/reconstructs facilities to their prior
existing/approved conditions at their prior existing locations.
The Flood-Flow Diversion Berm is located greater than 50-feet form the toe of the
subject potentially hazardous steep slopes and approximately 200-feet from
Lilliwaup Creek.
The purpose of this Berm is to prevent high flow velocities (high flow velocities
associated with any future High-Flood-Flow, similar to the December 2007 Flood
Flow) from reaching the Hatchery Rearing Tanks. Such high velocities
dislodged/displaced five 20' diameter tanks in December 2007.
5
This Berm does not measurably reduce flood plane storage volume, nor does it
prevent the Rearing Tank area from becoming flooded during future High-Flood-
Flows. Flood waters will fill the tank area by flowing with low velocities from south to
north instead of by high velocities from north to south.
No new Buffer or Setback requirements are necessary or recommended.
8. Clearing, Grading, and vegetation removal:
There is no clearing, grading or vegetation removal (common to most proposed
Actions), associated with this work. The Action does not involve moving into a new,
recently undisturbed land area.
The work associated with this Action involves restoring the original conditions of the
site to the conditions that existed before the December 2007 flood damages
occurred. The primary focus was to remove deleterious sediments, immediately
adjacent to the low flow Creek channel, so that they would not get introduced into
the low flow channel when normal winter high flows resume.
Here, the Action work involved removing thousands of yards of damaging sediments
from the Lilliwaup Creek regime and disposing them offsite.
Some deleterious sediment was removed from Creek Bars and Creek Banks
(immediately adjacent to the Creek low flow channel) and placed at nearby locations
as remote as possible from future high flowing creek conditions.
No new vegetation removal was part of this Action.
9. Temporary erosion control:
No temporary erosion control was required. All work was accomplished during very
low flow Creek conditions. No work was done within the wetted Creek low flow
channel.
The Action work actually removed deposits of flood flow caused sedimentation.
10.Analysis of onsite and offsite impacts of Action:
The Action restored the Lilliwaup Creek regime, onsite, where sediment removal
was permitted.
The Action also restored elements of the onsite Lilliwaup Hatchery.
6
The onsite removal of the deleterious sediments benefitted the offsite Lilliwaup
Creek regime by eliminating thousands of cubic yards of sediment that could
potentially migrate downstream and cause more sediment damage to those already
damaged downstream regime areas.
11.Vegetation management, drainage, erosion control, and buffer width specifications:
Action work primarily involved removing sediments from the Lilliwaup Creek
floodplain, where sparse brush and grasses and a few large trees were the only
natural ground cover that existed.
Sediments were removed to help save most of the existing large trees. All areas
where sediments were removed, or safely spread in upland areas, were covered
with loose straw to protect against erosion until natural Revegetation occurs.
Because this is a gravelly cobblely floodplain area, high flow disturbances maintain
the majority of the floodplain floor as exposed sand/gravel/rock with sparse
vegetation.
Woody debris was placed at locations where it might help arrest erosion during high
Creek flow or where the Creek might migrate into.
Other areas, including the Diversion Berm, where removed sediment was placed (as
safely as possible in upland areas) were covered with loose straw for Revegetation.
However, should extremely/unusually high flood flows, like those of December 2007,
return, it is possible that some of this material will be subject to erosion. It is not
possible to provide 100% protection everywhere at all times for all potential flood
flow occurrences.
No formal Drainage requirements were necessary, associated with this Action, nor
were any new Buffers necessary.
12.Proposed mitigation:
No other Formal Mitigation requirements are associated with the above described
Action. This Action work, is by nature, itself formal mitigation.
More importantly, none of the work, associated with this Action, impacts the subject
potentially hazardous steep slopes within 300-feet of the Action. The primary
purpose of this Geotechnical Report is to ascertain whether or not the Action will be
in jeopardy by existing unstable slopes or, by Action implementation, cause or
induce instability to otherwise stable steep slopes. The answer, in both cases, is no.
The above described Action is not in steep slope failure jeopardy nor will the Action
7
create steep slope instability. Therefore, no new mitigation measures are
recommended.
13.Site Plan Map:
Site Plan Map (1 of 2) is the third attachment to this document.
This completes this Geotechnical letter Report.
I, Kenneth W. Martig, Jr., PE, of Martig Engineering have completed this Geotechnical
Analysis as documented within this Letter Report and its attachments. I am familiar with
this site, having visited and inspected the site and its surrounds and evaluated pertinent
maps, documents and reports associated with the site. As presented herein, no
landslide hazards or significant environmental impacts will result t by virtue of this
Action
e ified by
AS,y (�
C �
neth W., artig PE r- ^' d
to N
Attachments: 1- ologic/Topographic Map (1" = 200'); 9F t �o
2- Mason County Soils Survey Map (1" = 500'); soNT
3- Site Plan (1" = 100');
4- Cross Section 9 - 9 (1" = 500'); (jFJlPIRES 1-9
5- Submittal Checklist for a Geotechnical Report
8
GEOLOGIClTOPOGRAPHIC MAP
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MASON COUNTY
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SOILS MAP
Scale: 1" = 500'
a. (Gh) , Grove gravelly sandy loam;
b. (Rc), Rough mountainous land,
Hoodsport soil material
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SITE PLAN MAP
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(Cross Section 9 — 9)
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