Attachment_5_-_PPNM_Stabilization_-_Appendix_D.pdf

APPENDIX D:

GEOTECHNICAL MONITORING TRIGGER ACTION RESPONSE

PLAN (TARP)

Barr Engineering Co. 4300 MarketPointe Drive, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com

Technical Memorandum

To: Joshua Helm and Guy Stickney, Bureau of Land Management Lee Petersen, Principal Engineer, Itasca Consulting Group, Inc.

From: Russell J. Sheets, P.E. (MT), Senior Geotechnical Engineer, Joel Swenson, Senior Geotechnical Engineer, Subject: Geotechnical Monitoring Trigger Action Response Plan (TARP) Date: April 12, 2022 Project: Pompeys Pillar National Monument Rock Stabilization – Rock Block Monitoring System c: File

Barr Engineering Co. (Barr), contracted by Itasca Consulting Group, Inc. (Itasca), assisted in design and implementation of a Rock Block Monitoring System (RBMS) at Pompeys Pillar National Monument located in Yellowstone County, Montana. This memorandum is the Trigger Action Response Plan (TARP) that accompanies the RBMS. The TARP provides the Bureau of Land Management (BLM) staff predetermined courses of action to be followed in the event that defined visual observations or monitoring thresholds are exceeded.

An explanation of the purpose and development of a TARP is presented in the Pompeys Pillar National Monument Rock Stabilization Phase 1 report dated August 28, 2020. This TARP is to a tool to manage geohazard risks of the Signature Block, Turtle Rock, and Lower Rock areas with respect to changed site observations, weather events, or monitoring data exceedances.

A limited rock RBMS (Phase 1) was implemented in July 2020 during to monitor the Signature Block area and Turtle Rock area. RBMS installation Phases 2 and 3 occurred in March 2021 and March 2022, respectively, adding a weather station and instrumentation to the Signature Block, Turtle Rock and Lower Block areas. The purpose of the initial RBMS was to provide a baseline understanding of current displacement and block rotation conditions and inform design and installation of an expanded RBMS to monitor additional geohazards identified by Itasca through site reconnaissance and design.

1.0 General TARP Layout

Barr developed the TARP framework for the Signature Block, Turtle Rock, and Lower Rock areas. On March 25, 2022, Itasca selected trigger levels based on data collected to date. Attachment 1 contains the TARP and trigger levels. The TARP developed for the Pompeys Pillar RBMS includes three key components.

These are defined as:

Ground Condition Trigger Events Response Plans

To: Joshua Helm and Guy Stickney, Bureau of Land Management, Lee Petersen, Itasca Consulting Group, Inc.

From: Russell J. Sheets, P.E., and Joel Swenson, Barr Engineering Co.

Subject: Geotechnical Monitoring Trigger Action Response Plan (TARP) Date: April 12, 2022 Page: 2

P:\Mpls\26 MT\55\26551004 Pompeys Pillar NA Monitoring\WorkFiles\TARP\Pompeys_Pillar_Geotechnical_Monitoring_TARP_Final.docx

A description and explanation of each component is provided in the following sections.

2.0 Ground Condition

The left-most column of the TARP defines the ground condition in terms of both a level rank and a color code. This provides a quick and efficient means to communicate the current geohazard risk condition to site staff and key stakeholders. In general, the Ground Condition Level increases as one evaluates above trigger limits. A general TARP may contain seven specific ground condition levels to describe the conditions of rock blocks based on visual observation, weather conditions, and instrumentation measurements:

Level 0: Normal Condition (White) Level 1: Non-Movement Condition for Review (Blue) Level 2: New Movement – Low Potential of Safety Impacts (Green) Level 3: Continual Movement – Moderate Potential of Safety Impacts (Yellow) Level 4: Accelerating Movement – High Potential of Safety Impacts (Orange) Level 5: Imminent Failure – High Risk of Safety Impacts (Red) Level 6: Active or Unexpected Failure

For this TARP, Levels 0, 1, and 2 are included. If observations and data collected exceeding Level 2 warrant additional technical analyses and risk review, it is recommended that the Pompeys Pillar Park staff meet with BLM engineers to discuss findings, engage the design Engineer of Record for direction, and determine Level 3 as indicated above.

3.0 Trigger Events

The center columns of the TARP specify the trigger events based upon the source. Each defined trigger source requires a predefined threshold or condition that is observed or exceeded to define the Ground Condition. The TARP includes the following trigger events:

Visual Observation Weather Crack Gauge Tiltmeter Distometer

These trigger event sources have been implement or previously used to characterize the site condition.

Additional methods could be implemented in the future if changing site conditions warrant additional monitoring approaches.

From: Russell J. Sheets, P.E., and Joel Swenson, Barr Engineering Co.

Subject: Geotechnical Monitoring Trigger Action Response Plan (TARP) Date: April 12, 2022 Page: 3

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The RBMS allows for quantitative evaluation of displacement, tilt and environmental factors (such as precipitation and temperature); therefore, specific displacement and rate magnitudes can be established to define conditions that require increased attention. If additional monitoring systems are implemented in the future, then they can be readily incorporated into the TARP.

The initial indication of a change will be changes in visual site observations, measurable displacement or rotation. As displacement or rotation rates increase to and above the March 25, 2022 trigger limits, then it may be necessary to reevaluate the trigger limits or apply other trigger limits in consultation with the design Engineer of Record for Ground Condition Level 3. Other examples of trigger limit types are:

statistical based, event driven (precipitation and/or temperature), increasing static displacement or rotation limits, velocity, acceleration, or inverse velocity.

The RBMS monitoring website currently has the trigger limits in place. Text and email notifications will be sent when the trigger limits have been exceeded. Access to the RBMS monitoring website access has been provided to the Pompeys Pillar Park Manager, BLM Staff, and Itasca.

4.0 Response Plans

The right columns of the TARP define the response plan when a specific trigger event is observed and the responsible person, or party, to complete the required actions. The response plan details decisions that key stakeholders previously have agreed upon, so that when the triggers occur, the responsible party is not determining the necessary course of action while a potential geohazard risk is occurring and time is critical. The response plan presented here contains the following components:

Action – this defines the step(s) to take, or controls to implement, when the associated trigger event occurs.

Monitoring – the change in block condition will require increased frequency of visual inspections and RBMS data review.

Responsible Party – the person or group with ownership to complete the Action and Monitoring associated with the Ground Condition Level.

Criteria to Downgrade – the premise of a TARP is to ensure controls exist to appropriately respond when geohazard risk increases; however, as the risk decreases there is specified criteria to allow the hazard to be downgraded in a similar manner.

Reporting – to ensure that all key stakeholders are aware and have ownership of geohazard risk, specific triggers require appropriate communication to those stakeholders

The actions and monitoring responses have been populated with representative items for similar geohazards with increasing risk as movement accelerates. The Pompeys Pillar Park staff and BLM must review these items and edit where necessary to ensure these align with risk-based conversations that have occurred over the course of the project.

From: Russell J. Sheets, P.E., and Joel Swenson, Barr Engineering Co.

Subject: Geotechnical Monitoring Trigger Action Response Plan (TARP) Date: April 12, 2022 Page: 4

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4.1 Responsible Party and Reporting

The expected responsible party and reporting level based on typical approaches for similar geohazards with increasing risk are listed based upon understanding of the project and site operation. These must be reviewed to ensure that they follow the actual site operation and management protocols. Additionally, if Pompeys Pillar Park staff and the BLM have an over-arching emergency response plan that is to be followed, then references to that plan and steps can be incorporated where applicable.

4.2 Criteria to Downgrade

The conditions that must be observed to define a decrease in the geohazard risk are to be agreed upon by the key stakeholders. Typical observations and monitoring trends have been included to provide guidance; however, as with the previously discussed items these must be vetted by the Pompeys Pillar Park and BLM staff, with consultation of the design Engineer of Record, to ensure that it is in alignment with the evaluation of on-going risk.

5.0 Closing

Barr has developed a TARP to assist the BLM with continual assessment of geohazard risks at Pompeys Pillar. The TARP table focuses on each specific area of interest: Signature Block area, Turtle Rock area, and Lower Rock area, and provides an approach for assessing geohazards and responses to mitigate the risk to visitors and on-site staff.

Attachments:

Table 1. Trigger Action Response Plan (TARP) for Pompeys Pillar National Monument, Montana

Vi su al O bs er va tio n W ea th er S ta tio n Cr ac km et er

Ti ltm et er

D is to m et er

Ac tio ns M on ito rin g

Re sp on si bl e

Pa rt y Cr ite ria to D ow ng ra de

Re po rt in g

Le ve l 0

Le ve l 1

Le ve l 2

1) N o ne w o r m ea su re ab le sig ns o f m ov em en t w ith in a w ee k pe rio d.

2) N o ad di tio na l r ai nf al l o ve r a ee k pe rio d.

In st ru m en t

Se ns or

ID

U pp er T rig ge r L im it Lo w er

T rig ge r L im it

U ni ts In st ru m en t Se ns or

ID

U pp er

T rig ge r L im it

Lo w er T rig ge r L im it U ni ts

Si g Bl oc k To p

CM

m m

Lo w er

Ro ck

Bl oc k A ax is

0.

0.

de g

Si g Bl oc k To p

CM

m m

Lo w er

Ro ck

Bl oc k B ax is

0.

0.

de g Si g Bl oc k To p

CM

m m

Lo w er

Ro ck

Bl oc k A ax is

0.

de g Si g Bl oc k

EF

CM

1.

0.

m m

Lo w er

Ro ck

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0.

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NF

CM

0.

0.

m m

Lo w er

Ro ck

Bl oc k A ax is

0.

0.

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NF

CM

0.

0.

m m

Lo w er

Ro ck

Bl oc k B ax is

0.

0.

de g Tu rt le Ro ck Bl oc k 1a

CM

5.

m m

Tu rt le Ro ck Bl oc k 2b

A ax is

0.

0.

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Tu rt le Ro ck Bl oc k 1b

CM

m m

Tu rt le Ro ck Bl oc k 2b

B ax is

0.

0.

de g

Tu rt le Ro ck Bl oc k 2a

CM

6.

m m

Si g Bl oc k

DM

m m

Tu rt le Ro ck Bl oc k

CM

2.

m m

Si g Bl oc k

DM

m m

Si g Bl oc k

DM

0.

m m

M ar ch

5, TA

RP

C ra ck m et er

L im its

M ar ch

5, TA

RP

T ilt m et er a nd D is to m et er L im its

1) R es um e an d m ai nt ai n vi su al in sp ec tio n sc he du le

2) R es um e an d m ai nt ai n m ov em en t m on ito rin g da ta co lle ct io n an d as se ss m en t a s sc he du le d.

1) C on du ct re gu la r v isu al in sp ec tio n of

S ig na tu re B lo ck

Ar ea a nd d oc um en t.

2) A dd re ss m al fu nc tio ni ng m on ito rin g eq ui pm en t, ac qu isi tio n eq ui pm en t, an d/ or vi al iza tio n pr og ra m

1) C on du ct w ee kl y do cu m en te d vi ec tio ns o f S ig na tu re

Bl oc k

Ar ea

2) R ev ie w S ig na tu re

B lo

Ar ea m ov em en t m on ito rin g da ta o n M on da ys

W ed ne sd ay s, an d

Fr id ay s.

M an ag er

Di st ric t E ng in ee r

(T ec hn ica l R ep or tin g)

M ai nt en an ce

W or ke r

M ai nt en an ce

W or ke r w ith a ss ist an ce fr om

M um en t M an ag er an or

D ist ric t E ng in ee r

M ai nt en an ce

W or ke r ai nt en an ce W or ke r w ith a ss ist an ce fr om um en t M an ag or D ist ric t E ng in ee r

M ai nt ai n M ai nt en an ce W or ke r N ot A pp lic ab le

N ot

A pp lic ab le N or m al C on di tio n

- N o ne si gn s o f m ov em en t

Ta bl e 1:

T rig ge r A ct io n R es po ns e

Pl an

(T A

R P) fo r P om pe y' s

Pi lla r N at io na l M on um en t, M on ta na

GR

O

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D C

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D

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N

TR

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GE

R

EV

EN

TS

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SP

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SE

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LA

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1) N o ne w si gn s o f t en sio n cr ac ks , r av el

, o r r oc kf al l ob se rv ed

1) N o sig ni fic an t ex pe ct ed p re cip ita tio n or ra pi d sn ow m el t.

1) N o sig ni fic an t ex pe ct ed p re cip ita tio n or ra pi d sn ow m el t.

1) N o sig ni fic an t e xp ec te d pr ec ip ita tio n or ra pi d sn ow m el t.

1) N o sig ni fic an t ex pe ct ed p re cip ita tio n ra pi d sn ow m el t.

1) M ai nt ai n m on th ly do cu m en te d vi ec tio ns

2) M ai nt ai n w ee kl y re vi ew o f m on ito rin g da ta

Re su m e m on ito rin g fre qu en cy or re

-e st ab lis h m ov em en t m on ito rin g da ta a cc es s.

M on um en t M an ag er N on -M ov em en t C on di tio n fo r R ev ie w

1) R eg ul ar v isu al in sp ec tio n no t c om pl et ed p sc he du le

1)

N ot a pp lic ab le

1) M on ito rin g da ta ot be g ac tiv el y co lle ct ed u na bl e to a cc es s a nd ew d at a.

1) M on ito rin g da ta g ac tiv el y co lle ct ed o r un ab le to a cc es s a nd v ie

1) M on ito rin g da ta g ac tiv el y co lle ct ed u na bl e to a cc es s a nd ew d at a.

1) In cr ea se v isu al in sp ec tio n an d do cu m en ta tio n fre qu en cy

N ew

M ov em en t - L ow

Po te nt ia l o f S af et y Im pa ct s 2)

N ew c ra ck s, ra ve l, ro fa ll th at w er e no t pr es en t d ur in g pr ev io us ec tio n.

2) In cr ea se fr eq ue nc y of ov em en t m on ito rin g re ew s.

1) O bs er va tio n of a pr ev io us c ha ng e in sl op e co nd iti on

; h ow ev er

, n o ac tiv e si gn s o f m ov em en t at ti m e of in sp ec tio n.

Se e M ar ch

5, TA

RP

Li its

Se e

M ar ch

5, Se e M ar ch

5,

1) R ai n pr ec ip ita tio n ev en t o f 0

.2 in o r gr ea te r i n a h r pe rio d.

3) D isc re tio n of M on um en t

M an ag er a nd

D ist ric t

En gi ne